Optical disc recording apparatus, computer-readable recording medium recording a file management program, and optical disc

ABSTRACT

An optical disc recording apparatus for recording a video object onto an optical disc. A recording area of the optical disc is divided into a plurality of zones which each include a plurality of adjacent tracks. The optical disc recording apparatus includes: a reading unit for reading from the optical disc the sector information showing data assignment for sectors on the optical disc; a recording unit for recording the video object onto the optical disc; and a control unit for controlling the reading unit and the recording unit. The control unit detects at least one series of consecutive unassigned sectors on the optical disc by referring to the read sector information. Each series has a total size greater than a minimum size and is located within a single zone. The minimum size corresponds to a data amount that ensures uninterrupted reproduction of the video object. The control unit also controls the recording unit to record the video object into the detected series.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] This invention relates to an optical disc recording apparatus, acomputer-readable recording medium recording a file management program,and an optical disc.

[0003] (2) Description of the Prior Art

[0004] Recently, recording mediums such as magneto optical discs (MO)have been widely used for recording data to be read by computers.Currently, practical uses of DVD (Digital Versatile Disc)-RAM discs arewaited for due to general expectation that DVD-RAMs will become a mainrecording medium of the next generation.

[0005] In conventional MOs, like HD (Hard Disc) or FD (Flexible Disc),the minimum unit in accessing data on discs is “sector” having severalkilobytes. Each file is recorded in one or more sectors.

[0006] Reading and writing of files from/onto discs are executed bycomputers as functions of a file system which is a part of operatingsystems (OS). A file system is defined, for example, in ISO/IEC13346.

[0007] According to a conventional technique, for example, whenrecording a file of 200 KB onto a recording medium with 2 KB-sectors,computers must find 100 unassigned sectors on the recording medium. The100 unassigned sectors need not be physically consecutive. For example,when four separate groups respectively having 30, 30, 30, and 10unassigned sectors are found on the recording medium, the file isdivided into the four groups of sectors. Each part of the file recordedin each group of sectors, namely each group of consecutive sectors, iscalled “extent”.

[0008] In such a conventional technique, files can be divided andrecorded into a plurality of extents. This provides a merit that all thesectors on a recording medium can be used efficiently even afterrecording and deleting of files on the medium are repeated a number oftimes.

[0009] However, conventional recording mediums and file systems have aproblem that uninterrupted reproduction of audio/video data (hereinafterreferred to as AV data) recorded on the recording mediums cannot beensured.

[0010] More specifically, when recording and deleting of files on arecording medium are repeated several times, the AV data may not berecorded in consecutive sectors. The AV data may be divided and recordedinto a plurality of extents, as described above. When this happens, thereproduction apparatus cannot achieve uninterrupted reproduction of theAV data due to a seek operation of an optical pickup that occurs as theoptical pickup moves between the plurality of extents.

[0011] For example, when a seek occurs between a sector at the innermostperiphery and a sector at the outermost periphery of a disc, the seektime amounts to several-hundred milliseconds. In case of moving images,such a seek of several-hundred milliseconds interrupts reproductionsince reproducing 30 frames per second is required for reproduction ofmoving images.

[0012] As described above, uninterrupted reproduction may not be ensuredby conventional file systems. This is especially a serious problem formass storages such as DVD-RAM on which, like VTR, a plurality of piecesof AV data (e.g., TV programs) can be recorded, edited, and deleted.

[0013] Here, it should be reminded that recording mediums can alsorecord computer data, as well as AV data. Accordingly, particularattention should be paid on how to efficiently store both types of dataon a disc.

SUMMARY OF THE INVENTION

[0014] It is therefore an object of the present invention to provide anoptical disc recording apparatus, a computer-readable recording mediumrecording a file management program, and an optical disc which ensureuninterrupted reproduction of AV data and record various types of dataincluding AV data together and efficiently.

[0015] The above object is achieved by an optical disc recordingapparatus for recording a video object on an optical disc, where arecording area of the optical disc is divided into a plurality of zoneswhich each include a plurality of adjacent tracks, and includes sectorinformation showing data assignment for sectors on the optical disc, theoptical disc recording apparatus including: a reading unit for readingthe sector information from the optical disc; a recording unit forrecording the video object onto the optical disc; and a control unit forcontrolling the reading unit and the recording unit, where the controlunit: detects at least one series of consecutive unassigned sectors onthe optical disc by referring to the read sector information, eachseries having a total size greater than a minimum size and being locatedwithin a single zone, the minimum size corresponding to a data amountthat ensures uninterrupted reproduction of the video object; andcontrols the recording unit to record the video object into the detectedseries.

[0016] With the above construction, the video object is recorded in aseries of consecutive unassigned sectors with the total size greaterthan a predetermined size, the series without including a zone boundary.This is achieved by searching of such a series of consecutive unassignedsectors prior to the recording of the video object onto the opticaldisc. The predetermined size is set so that the uninterruptedreproduction is ensured in any types of reproduction apparatuses. As aresult, the video object recorded by the present optical disc recordingapparatus is reproduced by any types of reproduction apparatuses withoutgaps in the reproduced video and audio images (without missing frames).Also, the record area is divided into a plurality of zone areas torealize rotation control called Z-CLV (Zone-Constant Linear Velocity)during recording and reproduction. By doing so, a qualified recordingefficience is achieved without sacrificing the recording density of theoutermost periphery of the optical disc. Also, the uninterruptedreproduction is ensured since the video object does not outstep the zoneboundary.

[0017] In the above optical disc recording apparatus, the recording areaof the optical disc may be divided into a plurality of 2 KB sectors,with each set of 16 consecutive sectors forming one ECC block, the videoobject is composed of a plurality of packs, each pack having a size of 2KB, the minimum size is the number of ECC blocks which is represented as“N_ecc” in the following formula: N_ecc=Vo*Tj/((16*8*2048)*(1−Vo/Vr)),where “Tj” represents a maximum jump time of an optical pickup of areproduction apparatus, “Vr” represents an input transfer rate (Mbps) ofa track buffer of the reproduction apparatus, and “Vo” represents aneffective output transfer rate (Mbps) of the track buffer.

[0018] With the above construction, the predetermined size for ensuringthe uninterrupted reproduction can be obtained in case defective sectorsare not included in the series of consecutive unassigned sectors.

[0019] In the above optical disc recording apparatus, the recording areaof the optical disc is divided into a plurality of 2 KB sectors, witheach set of 16 consecutive sectors forming one ECC block, the videoobject is composed of a plurality of packs, each pack having a size of 2KB, the minimum size is the number of ECC blocks which is represented as“N_ecc” in the following formula:N_ecc=dN_ecc+Vo*Tj/((16*8*2048)*(1−Vo/Vr)), where dN_ecc is a number ofECC blocks, in a series of consecutive unassigned sectors, that includedefective sectors, “Tj” represents a maximum jump time of an opticalpickup of an reproduction apparatus, “Vr” represents an input transferrate (Mbps) of a track buffer of the reproduction apparatus, and “Vo”represents an effective output transfer rate (Mbps) of the track buffer.

[0020] With the above construction, the predetermined size for ensuringthe uninterrupted reproduction can be obtained in case defective sectorsare included in the series of consecutive unassigned sectors.

[0021] In the above optical disc recording apparatus, the effectivetransfer rate Vo may be found according to the following formula:

Vo=(N _(—) pack*2048*8)*(27 M/(SCR _(—) first _(—) next−SCR _(—) first_(—) current)

[0022] where N_pack is the total number of packs included in the videoobject that should be recorded in N_ecc ECC blocks, SCR_first_current isa time (in 1/(27 mega) seconds) at which the track buffer of thereproduction apparatus should output the first pack of the video object,and SCR_first_next is a time (in 1/(27 mega) seconds) at which the trackbuffer of the reproduction apparatus should output the first pack of thefollowing video object.

[0023] With the above construction, it is possible to obtain, based onthe effective output transfer rate, the predetermined size for videoobjects with a variable bit rate. This achieves, for example, anefficient use of optical disc having a small amount of unassigned areas.

[0024] In the above optical disc recording apparatus, the control unitmay generate management information showing areas of the optical discwhere the video object has been recorded by the recording unit andcontrols the recording unit to record the generated managementinformation onto the optical disc, and when the reading unit reads outmanagement information from the optical disc, the control unit refers tothe read management information as well as the sector information todetect the series.

[0025] With the above construction in which the management informationis recorded on the optical disc, it is possible to detect unassignedareas at high speed and without difficulty.

[0026] The above object is also achieved by a computer-readablerecording medium prestoring a file management program for recording avideo object onto an optical disc, the file management program being tobe run by a computer which includes: a reading unit for reading datafrom an optical disc; and a recording unit for recording data onto theoptical disc, where a recording area of the optical disc is divided intoa plurality of zones which each include a plurality of adjacent tracks,and includes sector information showing data assignment for sectors onthe optical disc, the file management program including the followingsteps to be executed by the computer: a reading step for reading thesector information from the optical disc; a detecting step for detectingat least one series of consecutive unassigned sectors on the opticaldisc by referring to the read sector information, each series having atotal size greater than a minimum size and being located within a singlezone, the minimum size corresponding to a data amount that ensuresuninterrupted reproduction of the video object; and a recording step forrecording the video object into the detected series.

[0027] With the above construction in which the computer runs the filemanagement program, it is possible to record the video object into theseries of consecutive unassigned sectors which is larger than apredetermined size. This ensures the uninterrupted reproduction of thevideo object.

[0028] The above object is also achieved by a computer-readable opticaldisc including a data recording area, where the data recording area isdivided into a plurality of zones which each include a plurality ofadjacent tracks, and the data recording area includes: sectorinformation showing data assignment for sectors on the optical disc; andmanagement information showing areas of the optical disc where a videoobject has been recorded and are located within a single zone.

[0029] The above object is also achieved by a computer-readable opticaldisc including a data recording area, where the data recording area isdivided into a plurality of blocks which each include a plurality ofconsecutive sectors, and the data recording area includes: an area forrecording sector information showing data assignment for sectors on theoptical disc; and a management area for recording block informationshowing data assignment for blocks on the optical disc.

[0030] With the above construction, it is possible to record data inunits of sectors or blocks. Each block includes a plurality ofconsecutive sectors. Accordingly, even if one file is divided andrecorded into a plurality of extents, the size of the extent is largerthan the size of the block at the minimum. As a result, it is possibleto ensure the uninterrupted reproduction of the video data recorded onthe present optical disc by preventing interruptions which are cased byoccurrences of seek operations in the reproduction apparatus.Furthermore, data management in units of sectors and blocks areperformed together depending on the types of data. This achievesefficient use of the recording area of the optical disc.

[0031] In the above computer-readable optical disc, when the blockinformation shows that blocks have been assigned to data that is mainlycomposed of video data, the sector information may show that all sectorsin the assigned blocks have been assigned.

[0032] With the above construction, even if data is recorded by aconventional file system which uses a file management system managingdata in units of sectors, the blocks assigned to video data are notoverwritten by another data. Such a computer-readable optical disc issuitable for uninterrupted reproduction.

[0033] In the above computer-readable optical disc, a block sizerepresented as “L” may satisfy the following formula:

L>T*Vin*Vout/′(Vin−Vout),

[0034] where “L” (bits) represents the block size, “T” (seconds)represents a seek time of a reproduction apparatus, “Vin” represents aninput transfer rate (Mbps) of a buffer of the reproduction apparatus,and “Vout” represents an effective output transfer rate (Mbps) of thebuffer.

[0035] In the above computer-readable optical disc, when the blockinformation shows that blocks have been assigned to data that is notvideo data, the sector information may show that among sectors in theassigned blocks, only sectors recording the data have been assigned.

[0036] With the above construction, it is possible to record data otherthan video data (non-video) into unassigned sectors in blocks which havebeen assigned to non-video data. With this arrangement, even if videodata and other types of data are recorded in mixture, the uninterruptedreproduction is ensured, and both of video and other types of data arestored efficiently.

[0037] In the above computer-readable optical disc, the data recordingarea may be divided into a plurality of zones which each include aplurality of adjacent tracks, and each of the plurality of blocks isincluded in any one of the plurality of zones.

[0038] With the above construction, the record area is divided into aplurality of zone areas to realize Z-CLV. By doing so, a qualifiedrecording efficiency is achieved without sacrificing the recordingdensity of the outermost periphery of the optical disc. Also, theuninterrupted reproduction is ensured since the video object does notoutstep the zone boundary.

[0039] In the above computer-readable optical disc, blocks in each zonemay have the same size except a block that is adjacent to a zoneboundary, and the block that is adjacent to the zone boundary has a sizebeing equal to or larger than the size of the other blocks.

[0040] With the above construction, it is possible to use the datarecording area efficiently since one block in each zone has a sizelarger than the common size of the other blocks.

[0041] In the above computer-readable optical disc, the block that isadjacent to the zone boundary may include a sector having a maximumsector address in the current zone, and the management area includes amaximum block length table which shows, for each zone, sizes of blockswhich each include the sector having the maximum sector address in azone.

[0042] With the above construction, it is possible to managevariable-length blocks around the zone boundary without difficulty.

[0043] In the above computer-readable optical disc, an error correctioncode may be attached to every predetermined number of consecutivesectors, and each block may be composed of an integral multiple of thepredetermined number of consecutive sectors.

[0044] With the above construction, it is possible for therecording/reproducing apparatus to record and reproduce continuouslywithout generating overhead since each block is composed of an integralmultiple of the predetermined number of consecutive sectors.

[0045] The above object is also achieved by an optical disc recordingapparatus for recording data onto an optical disc which includes: a datarecording area divided into a plurality of sectors; and a managementarea for recording sector information showing data assignment forsectors on the optical disc and block information showing dataassignment for blocks on the optical disc, the optical disc recordingapparatus including: a reading unit for reading the block informationand the sector information from the optical disc; a judging unit forjudging a type of the data to record or delete the data, the type beingclassified into a first type and a second type; a first specifying unitfor, when the judging unit judges that the data is the first type,specifying, based on the read block information, either of: unassignedblocks in which the data is to be recorded: and blocks in which the datahas already been recorded; a second specifying unit for, when thejudging unit judges that the data is the second type, specifying, basedon the read sector information, either of: unassigned sectors in whichthe data is to be recorded; and sectors in which the data has beenrecorded; a data updating unit for either of recording and deletingfirst-type data into/from the blocks specified by the first specifyingunit and for either of recording and deleting second-type data into/fromthe sectors specified by the second specifying unit; and an assignmentupdating unit for updating at least one of the sector information andthe block information in accordance with operations of the data updatingunit.

[0046] With the above construction, it is possible to record data inunits of sectors or blocks. Each block includes a plurality ofconsecutive sectors. Accordingly, even if one file is divided andrecorded into a plurality of extents, the size of the extent is largerthan the size of the block at the minimum. As a result, it is possibleto ensure the uninterrupted reproduction of the video data recorded onthe present optical disc by preventing interruptions which are cased byoccurrences of seek operations in the reproduction apparatus.Furthermore, data management in units of sectors and blocks areperformed together depending on the types of data. This achievesefficient use of the recording area of the optical disc.

[0047] In the above optical disc recording apparatus, the assignmentupdating unit may include: a block information updating unit for, whenthe first specifying unit specifies unassigned blocks, updating theblock information by changing indication of the specified blocks from“unassigned” to “assigned”; and a sector information updating unit for,when the block information updating unit updates the block informationby changing indication of the specified blocks from “unassigned” to“assigned,” updating the sector information by changing indication ofall sectors included in the specified blocks from “unassigned” to“assigned.” With the above construction, even if data is recorded by aconventional file system which uses a file management system managingdata in units of sectors, the blocks assigned to video data are notoverwritten by another data. Such a computer-readable optical disc issuitable for uninterrupted reproduction.

[0048] In the above optical disc recording apparatus, the blockinformation updating unit, when the first specifying unit specifiesblocks which are assigned to a piece of first-type data to be deleted,updates the block information by changing indication of the specifiedblocks from “assigned” to “unassigned,” and the sector informationupdating unit, when the block information updating unit updates theblock information by changing indication of the specified blocks from“assigned” to “unassigned,” updates the sector information by changingindication of all sectors included in the specified blocks from“assigned” to “unassigned.” With the above construction, it is possibleto use the data recording area efficiently by recording the first-typedata and the second-type data in mixture since all the sectors in ablock are released when the first-type data is deleted.

[0049] In the above optical disc recording apparatus, the blockinformation may show whether each block is: (1) unassigned data; (2)assigned first-type data which is mainly composed of video data; or (3)assigned second-type data which is mainly composed of data other thanthe first-type data, where the assignment updating unit includes: afirst updating unit for updating the block information; and a secondupdating unit for updating the sector information, where the firstupdating unit, when the second updating unit updates the sectorinformation by changing indication of any sectors included in unassignedblocks to “assigned,” updates the block information by changingindication of the unassigned blocks from “unassigned” to “second-typedata assigned,” and the second updating unit, when the first updatingunit updates the block information by changing indication of blocks from“unassigned” to “first-type data assigned,” updates the sectorinformation by changing indication of all sectors included in the blocksto “assigned.”

[0050] With the above construction, it is possible to-manage the datarecording area without difficulty by recording the first-type data andthe second-type data in mixture.

[0051] The above object is also achieved by a computer-readablerecording medium prestoring a file management program for recording dataonto an optical disc which includes: a data recording area divided intoa plurality of sectors; and a management area for recording sectorinformation showing data assignment for sectors on the optical disc andblock information showing data assignment for blocks on the opticaldisc, the file management program including the following steps to beexecuted by the computer: a reading step for reading the blockinformation and the sector information from the optical disc; a judgingstep for judging a type of the data to record or delete the data, thetype being classified into a first type and a second type; a firstspecifying step for, when in the judging step it is judged that the datais the first type, specifying, based on the read block information,either of: unassigned blocks in which the data is to be recorded: andblocks in which the data has already been recorded; a second specifyingstep for, when in the judging step it is judged that the data is thesecond type, specifying, based on the read sector information, eitherof: unassigned sectors in which the data is to be recorded; and sectorsin which the data has been recorded; a data updating step for either ofrecording and deleting first-type data into/from the blocks specified bythe first specifying unit and for either of recording and deletingsecond-type data into/from the sectors specified in the secondspecifying step; and an assignment updating step for updating at leastone of the sector information and the block information in accordancewith operations in the data updating step.

[0052] With the above construction, it is possible to record data inunits of sectors or blocks. Each block includes a plurality ofconsecutive sectors. Accordingly, even if one file is divided andrecorded into a plurality of extents, the size of the extent is largerthan the size of the block at the minimum. As a result, it is possibleto ensure the uninterrupted reproduction of the video data recorded onthe present optical disc by preventing interruptions which are cased byoccurrences of seek operations in the reproduction apparatus.Furthermore, data management in units of sectors and blocks areperformed together depending on the types of data. This achievesefficient use of the recording area of the optical disc.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] These and other objects, advantages and features of the inventionwill become apparent from the following description thereof taken inconjunction with the accompanying drawings which illustrate a specificembodiment of the invention. In the drawings:

[0054]FIG. 1 shows the appearance and the recording area of the DVD-RAMdisc which is the optical disc of the present invention described inEmbodiment 1;

[0055]FIG. 2 shows the cross-section and surface of a DVD-RAM cut at theheader of a sector;

[0056]FIG. 3A shows the plurality of zone areas 0-23 and other areasprovided on a DVD-RAM;

[0057]FIG. 3B shows a horizontal arrangement of the zone areas 0-23 andother areas;

[0058]FIG. 3C shows logical sector numbers (LSNs) in the volume area;

[0059]FIG. 3D shows logical block numbers (LBNS) in the volume area;

[0060]FIG. 4 shows a hierarchical relation between zone areas, ECCblocks, and sectors;

[0061]FIG. 5 shows a last-block-length table;

[0062]FIG. 6 shows a sector management table and an AV block managementtable

[0063]FIG. 7 shows the AV block management table and the sectormanagement table (space bit map) which are both included in the filesystem management information recorded in the volume area;

[0064]FIG. 8 shows information included in the file system managementinformation other than the sector management table and the AV blockmanagement table shown in FIG. 6;

[0065]FIG. 9 shows a hierarchical directory structure corresponding tothe management information shown in FIG. 8;

[0066]FIG. 10 shows the linkage between the file entries and directoriesrewritten in accordance with the directory structure;

[0067]FIG. 11A shows a detailed data structure of file entry;

[0068]FIG. 11B shows the data structure of the allocation descriptor;

[0069]FIG. 11C shows an interpretation of upper two bits of extentlength of allocation descriptor;

[0070]FIG. 12A shows a detailed data structure of the fileidentification descriptors for directory;

[0071]FIG. 12B shows a detailed data structure of the fileidentification descriptors for file;

[0072]FIG. 13 shows a model of buffering of AV data into the trackbuffer, the AV data being read from the DVD-RAM disc by a reproductionapparatus

[0073]FIG. 14 shows the construction of a system including the opticaldisc recording/reproduction apparatus of the embodiment;

[0074]FIG. 15 is a block diagram showing the hardware structure of theDVD recorder 10;

[0075]FIG. 16 is a block diagram showing the construction of the MPEGencoder 2;

[0076]FIG. 17 is a block diagram showing the construction of the MPEGdecoder 4;

[0077]FIG. 18 is a function block diagram showing the construction ofthe DVD recorder 10 based on the functions of the components;

[0078]FIG. 19 shows the changes in the AV block management table and thespace bit map when AV data is recorded;

[0079]FIG. 20 shows the changes in the AV block management table and thespace bit map when AV data is deleted;

[0080]FIG. 21 shows a list of commands supported by the file system unit102 for the file management;

[0081]FIG. 22 shows an arrangement of buttons of the remote controller6;

[0082]FIG. 23 shows guidance images;

[0083]FIG. 24 shows the bit rate and resolution for each of the qualitytypes “high,” “standard,” and “time-ensuring;”

[0084]FIG. 25A is a flowchart showing the manual recording processperformed by the AV file system unit 103 of the DVD recorder unit 10;

[0085]FIG. 25B is a flowchart showing the programmed recording processperformed by the AV file system unit 103 of the DVD recorder unit 10;

[0086]FIG. 26 is a flowchart showing the process performed by the AVfile system unit 103 having received the AV-WRITE command;

[0087]FIG. 27 is a flowchart showing the process of deleting AV filesperformed by the common file system unit 104;

[0088]FIG. 28A shows AV files before and after deletion;

[0089]FIG. 28B shows the changes in the AV block management table andthe space bit map corresponding to the deletion;

[0090]FIG. 29 is a flowchart showing the process of recording non-AVfiles performed by the common file system unit 104;

[0091]FIG. 30 is a flowchart showing the process of deleting non-AVfiles performed by the common file system unit 104;

[0092]FIG. 31A shows non-AV files before and after deletion;

[0093]FIG. 31B shows the changes in the AV block management table andthe space bit map corresponding to the deletion;

[0094]FIG. 32 shows the second construction example of the AV blockmanagement table;

[0095]FIG. 33 shows the third construction example of the AV blockmanagement table;

[0096]FIG. 34 shows the fourth construction example of the AV blockmanagement table;

[0097]FIG. 35 shows the fifth construction example of the AV blockmanagement table;

[0098]FIG. 36A shows a specific example of the management information;

[0099]FIG. 36B shows a space bit map corresponding to the managementinformation shown in FIG. 36A;

[0100]FIG. 37 is a function block diagram showing the construction ofthe DVD recorder 10 of Embodiment 2 based on the functions of thecomponents;

[0101]FIG. 38 is a flowchart showing the recording process performed bythe AV recorder unit;

[0102]FIG. 39 shows a model of buffering of AV data into the trackbuffer in the reproduction apparatus;

[0103]FIG. 40 is a flowchart showing the recording process in the DVDrecorder of Embodiment 3;

[0104]FIG. 41 shows a free space list; and

[0105]FIG. 42 is a flowchart detailing the procedure of assigning thepseudo consecutive record.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] The following are the table of contents of the present section.

[0107] (1) Embodiment 1

[0108] (1-1) Optical Disc

[0109] (1-1-1) Physical Structure of Optical Disc

[0110] (1-1-2) File System Management Information (Part 1)

[0111] (1-1-3) File System Management Information (Part 2)

[0112] (1-1-4) Minimum Size of AV Block

[0113] (1-2-1) Entire System

[0114] (1-2-2) Hardware Structure of DVD Recorder 10

[0115] (1-2-3) Function Block Diagram

[0116] (1-2-4) Commands Executed by File system Unit 102

[0117] (1-3) Recording/Deleting

[0118] (1-3-1) Manual Recording of AV Data

[0119] (1-3-2) Programmed Recording of AV Data

[0120] (1-3-3) Deleting of AV Data

[0121] (1-3-4) Recording of Non-AV Data

[0122] (1-3-5) Deleting of Non-AV Data

[0123] (2) Embodiment 2

[0124] (2-1) Optical Disc

[0125] (2-1-1) Pseudo Consecutive Record

[0126] (2-1-2) Assignment of Pseudo Consecutive Records

[0127] (2-1-3) Pseudo Consecutive Record Assignment ManagementInformation and Space Bit Map

[0128] (2-2) Recording/Reproducing Apparatus

[0129] (2-2-1) System and Hardware Structure

[0130] (2-2-2) Function Block Diagram

[0131] (2-3-1) Recording of AV Files

[0132] (3) Embodiment 3

[0133] (3-1) Minimum Size of Pseudo Consecutive Record

[0134] (3-2) Recording of AV files

[0135] Now, an optical disc and an optical disc recording apparatus ofthe present invention are described in several embodiments with theabove-listed headings.

[0136] (1) Embodiment 1

[0137] (1-1) Optical Disc

[0138] (1-1-1) Physical Structure of Optical Disc

[0139]FIG. 1 shows the appearance and the recording area of a DVD-RAMdisc which is an optical disc. As shown in the figure, the DVD-RAM dischas a lead-in area at its innermost periphery and a lead-out area at itsoutermost periphery, with the data area in between. The lead-in arearecords the necessary reference signals for the stabilization of a servoduring access by an optical pickup, and identification signals toprevent confusion with other media. The lead-out area records the sametype of reference signals as the lead-in area.

[0140] The data area, meanwhile, is divided into sectors which are thesmallest unit by which the DVD-RAM can be accessed. Here, the size ofeach sector is set at 2 KB. The data area is also divided into aplurality of AV blocks which each are a group of consecutive sectors.The size of each AV block is set so that the uninterrupted reproductionthe reproduction apparatus is ensured even if a seek operation occurs.In the present embodiment, the size is set to about 7 MB. The data area,divided into sectors and AV blocks as described above, is managed asfollows. “Non-AV data, ” data other than AV data, is assigned areas inunits of sectors, while AV data is assigned areas in units of AV blocks.Non-AV data is managed in units of sectors; AV data is managed in unitsof AV blocks. Non-AV data is also recorded in sectors in AV blocks. EachAV block is managed not to include AV data and non-AV data in mixture.

[0141]FIG. 2 shows the cross-section and surface of a DVD-RAM cut at theheader of a sector. As shown in the figure, each sector is composed of apit sequence that is formed in the surface of a reflective film, such asa metal film, and an uneven part.

[0142] The pit sequence is composed of 0.4 μm˜1.87 μm pits that arecarved into the surface of the DVD-RAM to show the sector address.

[0143] The uneven part is composed of a concave part called a “groove”and a convex part called a “land”. Each groove and land has a recordingmark composed of a matal film capable of phase change attached to itssurface. Here, the expression “capable of phase change” unit that therecording mark can be in a crystalline state or a non-crystalline statedepending on whether the metal film has been exposed to a light beam.Using this phase change characteristic, data can be recorded into thisuneven part. While it is only possible to record data onto the land partof an MO disc, data can be recorded onto both the land and the grooveparts of a DVD-RAM, meaning that the recording density of a DVD-RAMexceeds that of an MO disc. Error correction information is provided ona DVD-RAM for each group of 16 sectors. In the present embodiment, eachgroup of 16 sectors that is given an ECC (Error Correcting Code) iscalled an ECC block.

[0144] On a DVD-RAM, the data area is divided into a plurality of zoneareas to realize rotation control called Z-CLV (Zone-Constant LinearVelocity) during recording and reproduction.

[0145]FIG. 3A shows the plurality of zone areas provided on a DVD-RAM.As shown in the figure, a DVD-RAM is divided into 24 zone areas numberedzone 0 to zone 23. Each zone area is a group of tracks that are accessedusing the same angular velocity. In this embodiment, each zone areacontains 1888 tracks. The rotational angular velocity of the DVD-RAM isset separately for each zone area, with this velocity being higher thecloser a zone area is located to the inner periphery of the disc. Thisensures that the optical pickup can move at a constant velocity whileperforming access within a single zone area. By doing so, the recordingdensity of DVD-RAM is raised, and rotation control is made easier duringrecording and reproduction.

[0146]FIG. 3B shows a horizontal arrangement of the lead-in area, thelead-out area, and the zone area 0-23 that were shown in FIG. 3A.

[0147] The lead-in area and lead-out area each have a DMA (DefectManagement Area) inside. The DMA records: position information showingthe positions of sectors found to include defects; and replacementposition information showing the positions of the sectors replacing thedefective sectors located in a replacement area.

[0148] Each zone area has a user area on the inside, and the replacementarea and an unused area are provided at the boundary between zone areas.The user area is an area that can be used by the file system as arecording area. The replacement area is used to replace defectivesectors when such defective sectors are found. The unused area is anarea that is not used for recording data. Only two tracks are assignedas the unused area, with such unused area being provided to preventmistaken identification of sector addresses. This is because whilesector addresses are recorded at a same position in adjacent trackswithin the same zone, for Z-CLV the sector addresses are recorded atdifferent positions in adjacent tracks at the zone boundary.

[0149] In this way, sectors which are not used for data recording existat the boundaries between zone areas. Therefore, on a DVD-RAM logicalsector numbers (LSN: Logical Sector Number) are assigned to physicalsectors of the user area in order starting from the inner periphery toconsecutively show only the sectors used for recording data.

[0150] As shown in FIG. 3C, the area that records user data and iscomposed of sectors that have been assigned LSNs is called volume area.

[0151] Also, as shown in FIG. 3D, in the innermost and outermostperipheries, volume structure information is recorded to be used to dealwith the disc as a logical volume. The rest of the volume area exceptthe areas for recording the volume structure information is calledpartition area. The partition area records files. The logical blocknumbers (LBN: Logical Block Number) are assigned to sectors of thepartition area in order starting from the first sector.

[0152]FIG. 4 shows a hierarchical relation between zone areas, ECCblocks, and sectors. As shown in the drawing, each zone area includes224 ECC blocks (3584 sectors). However, the number of sectors in a zoneis not necessary be an integral multiple of 224, or the number of ECCblocks. Therefore, the size of the last AV block in a zone is set tolarger than 224 ECC blocks so that the number of sectors in a zonebecomes an integral multiple of 224. For this purpose, DVD-RAM discsrecord a table which shows the size of the last block in each zone, as apart of management information.

[0153]FIG. 5 shows a last-block-length table. The last-block-lengthtable shows, for each zone, the length of the last AV block related to“last LBN.” The length of the last AV block is represented by the numberof ECC blocks included in the AV block. The “last LBN” column shows theLBN of the last sector (zone end), namely, the last sector adjacent tothe zone boundary, to indicate the position of the zone boundary.

[0154] As described above, the length of the last AV block is set to avariable-length. This prevents each AV block from including a zoneboundary. With this arrangement, it is possible to use the recordingarea on the disc efficiently.

[0155] (1-1-2) File System Management Information (Part 1)

[0156] Here, the file system structure of DVD-RAM is described. The filesystem of the present embodiment complies with ISO/IEC13346. Inaddition, the file system manages the AV data in units of AV blocks.

[0157]FIG. 6 shows a sector management table and an AV block managementtable. The sector management table is recorded in the partition area ofthe volume area and is included in the file system managementinformation. The drawing also shows a hierarchical relation between thevolume area, sectors, and contents of the sectors.

[0158] The first layer shows the volume area shown in FIG. 3D.

[0159] The second layer shows sector areas which includes the sectormanagement table and the AV block management table. The sector areas areincluded in the partition area. The sector management table (also calleda space bit map) showing the data assignment status for each sector isrecorded in the sector areas with LBNs 0-79. The AV block managementtable showing the data assignment status for each AV block is recordedin the sector areas with LBNs 84 and 85.

[0160] As shown in the third layer, the “space bit map” column showswhether each sector included in the partition area is assigned ornot-assigned. In this example, the assignment state of each sector isindicated by one bit. For example, each sector for logical block numbers0-79 is given bit “0” (indicating “assigned”) since these sectors havealready been assigned as a space bit map. Similarly, each sector forlogical block numbers 0-84 is given bit “0” (assigned) since thesesectors have already been assigned as the AV block management block. Asunderstood from these examples, each bit in the space bit map is writtenas “0” when a file or a part of a file is to be recorded or has beenrecorded by the user or the application in the current sector, otherwisewritten as “1.”

[0161] The AV block shown in the third layer shows for each AV block inthe partition area, with two bits for each AV block, whether the currentAV block is unassigned (00), assigned to AV data (01), assigned tonon-AV data (10), or reserved (11). For example, the AV block 0 is givenbits “10” (indicating “assigned to non-AV data”) since the AV block 0has already been assigned as the space bit map and the AV blockmanagement table which are both non-AV data. When certain AV blocks areshown as assigned to AV data in the AV block management table, all thesectors included in the AV blocks are shown as assigned in the space bitmap. This makes it possible to prevent mixture of AV and non-AV data ineach AV block, and secures AV data consecutive recording areas.

[0162]FIG. 7 shows relationships between the AV block management tableand the space bit map.

[0163] On the left-hand side of the figure, the AV block managementtable is shown. The table includes an arrangement of a plurality ofpieces of two-bit data which each shows the assignment status of AVblock. In this example, the AV blocks (AV_BLK in the drawing) #0-#2 arewritten as “10” (non-AV data); the AV blocks #3-#75 are written as “01”(AV data); and the AV blocks #76 and after are written as “00”(unassigned).

[0164] On the right-hand side of the figure, the space bit map is shown.In this example, the assignment status of the sectors included in the AVblocks #0, #3, and #79 is shown in the blocks encircled by dotted lines.The AV block #0 has been assigned to non-AV data. As a result, in acorresponding part in the space bit map, it is shown that sectors havingbeen recorded non-AV data are written as “0” (assigned); sectors havingnot been recorded non-AV data are written as “1” (unassigned). The AVblock #3 has been assigned to AV data. As a result, in a correspondingpart in the space bit map, it is shown that all the sectors are writtenas “0” (assigned). The AV block #79 has not been assigned yet. As aresult, in a corresponding part in the space bit map, it is shown thatall the sectors are written as “1” (unassigned).

[0165] It should be noted here that the AV block management table may berecorded as data for the file system, as the space bit map is, or may berecorded as one file. In the latter case, the AV block management tableis managed as a non-AV data file.

[0166] In the present embodiment, the AV block management table has atable structure. However, it may have a list structure.

[0167] (1-1-3) File System Management Information (Part 2)

[0168]FIG. 8 shows information included in the file system managementinformation other than the sector management table and the AV blockmanagement table shown in FIG. 6. The drawing shows hierarchically thevolume area, sectors, and the contents of the sectors. The arrows{circle over (1)}-{circle over (7)} show the order in which the storageposition of the file “Movie1.VOB” is detected in accordance with themanagement information shown in the drawing.

[0169] The first layer of the drawing shows the volume area shown inFIG. 3D.

[0170] The second layer shows various kinds of management informationsuch as a file set descriptor, end descriptor, file entry, anddirectory. These kinds of information comply with the file systemdefined in ISO/IEC13346. The file system defined in ISO/IEC13346achieves a hierarchical directory management. FIG. 9 shows ahierarchical directory structure corresponding to the managementinformation shown in FIG. 8. In FIG. 9, ovals represent directories, andrectangles represent files. The root directory branches to a directory“VIDEO” and two files “File1.DAT” and “File2.DAT.” The directory “VIDEO”branches to three files “Movie1.VOB,” “Movie2.VOB,” and “Movie3.VOB.”The management information of FIG. 8 corresponds to the directorystructure. Note that each file recording area shows only “Movie1.VOB.”in this example.

[0171] The file set descriptor with LBN 80 in the second layer shows anLBN of a sector in which a file entry of the root directory is recorded.The end descriptor with LBN 81 shows the end of a file set descriptor.

[0172] Each file entry (e.g., LBN 82, 584, or 3585) is recorded for eachfile (including directory) and shows a storage position of a file or adirectory. File entries for files and directories have the same formatso that a hierarchical directory structure can be constructed as onedesires.

[0173] Each directory (e.g., LBN 83, or 585) shows a storage position ofa file entry for each file and each directory included in a directory.

[0174] The third layer of this example includes three file entries andtwo directories. The file entries and directories are traced by the filesystem, and have a data structure constructed so that a storage positionof a predetermine file can be traced no matter how the directorystructure is constructed.

[0175] Each file entry includes an allocation descriptor showing astorage position of a file or a directory. When the file or thedirectory is divided into a plurality of extents, the file entryincludes a plurality of allocation descriptors for each extent. Forexample, file entries with LBN 82 and 584 each include one allocationdescriptor. This means that none of these files is divided into aplurality of extents. In contrast, the file entry with LBN 3585 includestwo allocation descriptors, indicating that the file is composed of twoextents.

[0176] Each directory includes a file identification descriptor showing,for each file and directory included in the current directory, a storageposition of the current file entry. As indicated by the file entries anddirectories shown in this figure, the storage position of the file“root/video/Movie1.VOB” is traced in the order of: file setdescriptor→{circle over (1)}→file entry (root)→{circle over(2)}→directory (root)→{circle over (3)}→file entry (video)→{circle over(4)}→directory (video)→{circle over (5)}→file entry (Movie1)→{circleover (6)}{circle over (7)}→file (extents #1 and #2 of Movie1.VOB).

[0177]FIG. 10 shows the linkage between the file entries and directoriesrewritten in accordance with the directory structure. In the drawing,the root directory includes file identification descriptors respectivelyfor: a parent dierectory (the parent of the root is the root itself), aVIDEO directory, file “File1.DAT,” and file “File2.DAT.” Also, the VIDEOdirectory includes file identification descriptors respectively for: aparent dierectory (root), file “Movie1.VOB,” file “Movie2.VOB,” and file“Movie3.VOB.” The storage position of file “Moviel.VOB” is detected bytracing in the order of {circle over (1)} to {circle over (6)}{circleover (7)}.

[0178]FIG. 11A shows a detailed data structure of file entry. As shownin the drawing, the file entry includes a descriptor tag, ICB tag,allocation descriptor length, extension attribute, and allocationdescriptor. “BP” in the drawing represents a bit position, and “RBP”represents a relative bit position.

[0179] The descriptor tag is a tag that shows the current piece ofinformation is a file entry. DVD-RAM includes a various types of tagssuch as a file entry descriptor, a space bit map descriptor, or thelike. Each file entry includes a descriptor tag written as “261” showingthat the current piece of information is a file entry.

[0180] The ICB tag shows attribute information related to the currentfile entry.

[0181] The extension attribute is information showing a higher-levelattribute than the contents defined in the attribute information fieldin the file entry.

[0182] The allocation descriptor field stores as many allocationdescriptors as the number of extents in the file. The allocationdescriptor shows an LBN indicating a storage position of an extent in afile or a directory. FIG. 11B shows the data structure of the allocationdescriptor. In the drawing, the allocation descriptor includes dataindicating an extent length and includes an LBN indicating a storageposition of an extent. Note that the upper two bits of the dataindicating an extent length shows the storage status of the extentrecording area, as shown in FIG. 11C.

[0183]FIG. 12A and 12B respectively show a detailed data structure ofthe file identification descriptors for directory and file. These twotypes of the file identification descriptors have the same format: eachdescriptor includes: management information, identification information,directory name length, an address showing the address, represented by anLBN, of the file entry of a directory or a file, information forextension, and directory name. With such an arrangement, an address of afile entry corresponding to a directory name or a file name isidentified.

[0184] (1-1-4) Minimum Size of AV Block

[0185] Here, the size of the AV block shown in the lower part of FIG. 4is described.

[0186] Each AV block except the last one in each zone is composed of 224ECC blocks, where each ECC block has about 7 MB. To ensure theuninterrupted reproduction of AV data, the minimum size of AV block isdetermined in relation with the buffer of the reproduction apparatus.

[0187]FIG. 13 shows a model of buffering of AV data into the trackbuffer, the AV data being read from the DVD-RAM disc by a reproductionapparatus.

[0188] In the upper part of FIG. 13, the AV data read from the DVD-RAMdisc is subjected to the ECC process. The processed AV data is thentemporarily stored in the track buffer (FIFO memory), and is sent to thedecoder. In the drawing, “Vin” represents an input transfer rate(minimum value) of the track buffer (rate of data read from an opticaldisc), and “Vout” represents an output transfer rate (maximum value) ofthe track buffer, where Vr>Vo. In this model, Vin=8 Mbps and Vout=11Mbps.

[0189] The lower part of FIG. 13 is a graph showing the change in thedata amount of the track buffer in this model. In the graph, thevertical axis represents the data amount of the track buffer; thehorizontal axis represents time.

[0190] The “T1” represents a time required for reading out the entire AVdata recorded in the pseudo consecutive record #j. In this period T1,the data amount of the track buffer increases at the rate of (Vin−Vout).

[0191] The “T2” (also referred to as a jump period) represents themaximum time taken by the optical pickup for jumping from the AV block#j to AV block #k (for example, it jumps from the innermost circuit tothe outermost circuit). The jump period includes the seek time of theoptical pickup and the time required for the rotation of the opticaldisc to be stabilized. In this period T2, the data amount of the trackbuffer decreases at the rate of Vout. This is the same in the period T4.

[0192] The size of the AV block is obtained as follows, where the sizeis represented as L bytes.

[0193] In the period T2, AV data is read from the track buffer. Onlythis is performed. If the buffer capacity becomes 0 during this period,an underflow occurs to the decoder. When this happens, the uninterruptedreproduction of the AV data cannot be ensured.

[0194] Here, to ensure the uninterrupted reproduction of the AV data(not to generate the underflow), the following formula need besatisfied.

[0195] <Formula 1>

(storarge amount B)≧(read-out amount R)

[0196] The storarge amount B is the amount of data that has beenaccumulated in the track buffer at the end of the period T1. Theread-out amount R is the total amount of data read during the period T2.

[0197] The storarge amount B is calculated using the following formula.

[0198] <Formula 2>

(storarge amount B)=(period T1)*(Vin−Vout)

=(read out time of one AV block) *(Vin−Vout)

=(AV block size L/Vin)*(Vin−Vout)

[0199] The read-out amount R is calculated using the following formula.It is considered that the maximum jump period Tj will be about 1.5seconds in the worst case.

[0200] <Formula 3>

(Read-out amount R)=T2*Vout

=(maximum jump period Tj)*Vout

=1.5 sec*8Mbps

=12 megabits

=1.5 MB

[0201] Replacing both sides of the Formula 1 respectively by Formula 2and Formula 3 gives us the following formula.

[0202] <Formula 4>

(L/Vin)*(Vin−Vout)≧Tj*Vout

[0203] From the Formula 4, it is derived that the AV block size L shouldsatisfy the following formula.

[0204] <Formula 5>

L ≧Tj*Vin*Vout/(Vin−Vout)

≧1.5 sec*11 Mbps*8 Mbps/(11 Mbps−8 Mbps)

≧44 megabits

≧5.5 MB

[0205] From the above consideration, it is found that when AV data isrecorded in a consecutive sectors of 5.5 MB in one AV block,uninterrupted reproduction is secured even if a jump occurs between AVblocks. The minimum size of AV block to ensure uninterruptedreproduction is 5.5 MB. In the present embodiment, the AV block size isset to 7.2 MB. This is because a margin is included in the value, takingan occurrence of a disc error or the like into account. Also, the trackbuffer capacity should have 1.5 MB at the minimum to prevent anoccurrence of underflow.

[0206] (1-2-1) Entire System

[0207]FIG. 14 shows the construction of a system including the opticaldisc recording/reproduction apparatus of the present embodiment.

[0208] The system includes an optical disc recording/reproductionapparatus 10 (also referred to as DVD recorder 10), a remote controller6 used for operating the DVD recorder 10, a DVD recorder display 12connected to the DVD recorder 10, and a receiver 9.

[0209] After the DVD-RAM disc is loaded, the DVD recorder 10 compressesthe video/audio data which is included in the analog broadcasting waveswhich is received through the receiver 9, records the compressed data,with the AV block as the minimum unit, into the DVD-RAM disc, expandsthe compressed video/audio data, and outputs the expanded video/audiosignals onto a display 12.

[0210] (1-2-2) Hardware Structure of DVD Recorder 10

[0211]FIG. 15 is a block diagram showing the hardware structure of theDVD recorder 10.

[0212] The DVD recorder 10 includes a control unit 1, an MPEG encoder 2,a disc access unit 3, an MPEG decoder 4, a video signal processing unit5, a remote controller 6, a bus 7, a remote controller signal receivingunit 8, and a receiver 9.

[0213] The control unit 1 includes a CPU1 a, a processor bus 1 b, a businterface 1 c, and a main memory 1 d. The control unit 1 executes aprogram stored in the main memory 1 d to control the entire DVD recorder10 in terms of recording, reproducing, editing, etc. Especially, thecontrol unit 1 controls the DVD recorder in accordance with the filesystem when AV data is recorded in the DVD-RAM disc in the minimum unitsof AV blocks.

[0214] The MPEG encoder 2 compresses the video/audio data which isincluded in the analog broadcasting waves received through the receiver9 and generates an MPEG stream.

[0215] The disc access unit 3, having a track buffer 3 a, under thecontrol of the control unit 1, records the MPEG stream received from theMPEG encoder 2 into the DVD-RAM disc via the track buffer 3 a, reads outthe MPEG stream from the DVD-RAM disc, and outputs the read MPEG streamto the MPEG decoder 4 via the track buffer 3 a.

[0216] The MPEG decoder 4 expands the compressed MPEG-stream which isread out by the disc access unit 3, and outputs the expanded video dataand audio signals.

[0217] The video signal processing unit 5 converts the video data outputfrom the MPEG decoder 4 into video signals for the display 12.

[0218] The remote controller signal receiving unit 8 receives remotecontroller signals from the remote controller 6 and informs the controlunit 1 of which operation the user has instructed.

[0219] The DVD recorder 10 is, as shown in FIG. 14, constructed based onthe premise that it is used as a replacement for a VTR used at home. Notlimited to the construction, when the DVD-RAM disc is to be used as arecording medium for computers, the following constructions arepossible. That is to say, the disc access unit 3 is connected, as aDVD-RAM drive apparatus, to a computer bus via an IF called SCSI or IDE.Also, the components other than the disc access unit 3 shown in FIG. 15are achieved or operated when the OS and the application program areexecuted on the computer hardware.

[0220]FIG. 16 is a block diagram showing the construction of the MPEGencoder 2. As shown in the drawing, the MPEG encoder 2 includes a videoencoder 2 a, a video buffer 2 b for storing the output of the videoencoder, an audio encoder 2 c, an audio buffer 2 d for storing theoutput of the audio encoder, a system encoder 2 e for multiplexing theencoded video data and audio data respectively stored in the videobuffer 2 b and the audio-buffer 2 d, an STC (System Time Clock) unit 2 ffor generating sync clock signals for the encoder 2, and an encodercontrol unit 2 g for controlling and managing these units.

[0221] The encoder control unit 2 g sends information such as the GOPinformation and the picture information to the control unit 1 shown inFIG. 15 every time a VOBU is generated in the encoding. Here, the GOPinformation includes the number of packs in the VOBU and the number ofpacks in the first I-picture in the VOBU. The packs mentioned here are,for example, video packs (V_PACK) and audio packs (A_PACK) shown in FIG.10, each having a fixed length of 2 KB. Accordingly, in the presentembodiment, the GOP information indicates the number of sectors assignedto the VOBU and the number of sectors assigned to first I-picture in theVOBU.

[0222]FIG. 17 is a block diagram showing the construction of the MPEGdecoder 4. As shown in the drawing, the MPEG decoder 4 includes ademultiplexor 4 a for dividing MPEG streams into video streams and audiostreams, a video buffer 4 b for temporarily storing the divided videostreams, a video decoder 4 c for decoding the video streams stored inthe video buffer 4 b, an audio buffer 4 d for temporarily storing thedivided audio streams, an audio decoder 4 e for decoding the audiostreams stored in the audio buffer 4 d, an STC (System Time Clock) unit4 f for generating sync clock signals, an adder 4 g for adding offsetvalues to the sync clock signals, and selectors 4 h-4 j, for selectingeither a sync clock signal or a sync clock signal added with an offsetvalue and supplying the selected signal to the demultiplexor 4 a, audiodecoder 4 e, and video decoder 4 c, respectively.

[0223] It should be noted here that the MPEG decoder 4 shown in thedrawing may be constructed the same as ordinary MPEG decoders in whichthe selectors 4 h to 4 j and adder 4 g are not included.

[0224] (1-2-3) Function Block Diagram

[0225]FIG. 18 is a function block diagram showing the construction ofthe DVD recorder 10 based on the functions of the components. Eachfunction shown in the figure is achieved after the CPU 1 a in thecontrol unit 1 executes the program in the main memory 1 d to controlthe hardware shown in FIG. 14.

[0226] As shown in FIG. 18, the DVD recorder 10 is composed of a discrecording unit 100, a disc reading unit 101, a file system unit 102, arecording/editing/reproducing control unit 105, a user IF unit 106, anAV data recording unit 110, an AV data editing unit 120, and an AV datareproducing unit 130.

[0227] The disc recording unit 100, on receiving a logical sector numberand logical data in units of sectors from the file system unit 102,records the received logical data onto the disc in units of ECC blocks(each block composed of 16 sectors). If the logical data has less than16 sectors, the disc recording unit 100 reads the ECC block, executesthe ECC process, then writes the ECC block onto the disc.

[0228] The disc reading unit 101, on receiving a logical sector numberand the number of sectors from the file system unit 102, reads data inunits of ECC blocks, subjects the read data to the ECC process, thetransfers only necessary sector data to the file system unit. This isbecause by reading AV data in units of ECC blocks (each block composedof 16 sectors), overhead is reduced. This is the same with the discrecording unit 100.

[0229] The file system unit 102 includes an AV file system unit 103 formainly writing and editing AV files, and a common file system unit 104for executing processes common to AV files and non-AV files. The filesystem unit 102, on receiving commands from the AV data recording unit110, AV data editing unit 120, and AV data reproducing unit 130 inrelation to writing or reading files, manages files on the optical discin units of sectors at the minimum.

[0230] Among various types of file management functions performed by thefile system unit 102, (a) recording AV data, (b) deleting AV data, (c)recording non-AV data, and (d) deleting non-AV data are explained.

[0231] (a) Recording AV Data

[0232] On receiving a command to record AV data from the AV datarecording unit 110 or the like, the AV file system unit 103 updates theAV block management table by assigning an AV block written as “00”(unassigned) to the specified AV data. The AV file system unit 103 thenrecords the AV data into the assigned AV block via the disc recordingunit 100. After this, the AV file system unit 103 updates the AV blockmanagement table by writing the assigned AV block as “01” (for AVblock), and updates the space bit map by writing all the sectorsincluded in the assigned AV block as “0” (assigned).

[0233]FIG. 19 shows the changes in the AV block management table and thespace bit map when AV data is recorded.

[0234] The left-hand side of the drawing shows change of the two-bitdata in the AV block management table showing the assignment status ofthe AV block #n. The right-hand side of the drawing shows change of apart of the space bit map corresponding to the sectors included in theAV block #n. As shown in the drawing, when the status of the AV block #nin the AV block management table is changed from “00” (unassigned) to“01” (for AV data), the statuses of all the sectors included in the AVblock #n are changed from “1” (unassigned) to “0” (assigned). With thisarrangement, each AV block does not include a mixture of AV data andnon-AV data, and a consecutive recording area is assigned to AV data asan AV block.

[0235] (b) Deleting AV Data

[0236] On receiving a command to delete AV data from the AV data editingunit 120, the AV file system unit 103 updates the AV block managementtable by writing an AV block recording the specified AV data as “00”(unassigned). The AV file system unit 103 then updates the space bit mapby writing all the sectors included in the current AV block as “1”(unassigned).

[0237]FIG. 20 shows the changes in the AV block management table and thespace bit map when AV data is deleted. As shown in the drawing, when thestatus of the AV block #n in the AV block management table is changedfrom “01” (for AV data) to “00” (unassigned), the statuses of all thesectors included in the AV block #n are changed from “0” (assigned) to“1” (unassigned).

[0238] (c) Recording Non-AV Data

[0239] On receiving a command to record non-AV data from therecording/editing/reproducing control unit 105, the common file systemunit 104 detects unassigned sectors which are written as “1”(unassigned) in the space bit map and are included in the AV blockswritten as “10” (for non-AV) in the AV block management table, andassigns the detected sectors to the specified non-AV data. The commonfile system unit 104 then records the non-AV data into the assignedsectors via the disc recording unit 100. After this, the common filesystem unit 104 updates the space bit map by writing the sectors havingrecorded the non-AV data as “0” (assigned). When not able to findunassigned sectors which are written as “1” (unassigned) in the spacebit map and are included in the AV blocks written as “10” (for non-AV)in the AV block management table, the common file system unit 104assigns sectors in an AV block written as “00” (unassigned) to thespecified non-AV data, updates the AV block management table by changingthe status of the AV block to “10” (for non-AV), and updates the spacebit map changing the statuses of the sectors to “0” (assigned).

[0240] (d) Deleting non-AV Data

[0241] On receiving a command to delete non-AV data from therecording/editing/reproducing control unit 105, the common file systemunit 104 updates the space bit map by changing the statuses of all thesectors recording the specified non-AV data to “1” (unassigned). When itis found from the AV block management table that one AV block isoccupied by the sectors with status “1” (unassigned) by the aboveprocess, the common file system unit 104 updates the AV block managementtable by changing the status of the AV block from “10” (for non-AV data)to “00” (unassigned).

[0242] The recording/editing/reproducing control unit 105 controls theentire DVD recorder 10. More specifically, the control unit 105 controlsdisplay of guidance which urges the user to operate, receivesinstructions from the user reacting to the guidance via the user IF unit106, and, in accordance with the user instructions, requests the AV datarecording unit 110, AV data editing unit 120, or AV data reproducingunit 130 to execute operations such as newly recording of AV data, andreproducing and editing of recorded AV data.

[0243] The user IF unit 106 receives instructions for operations fromthe user via the remote controller 6, and informs the received userinstructions to the recording/editing/reproducing control unit 105.

[0244] The AV data recording unit 110, AV data editing unit 120, and AVdata reproducing unit 130, on receiving a recording request from thecontrol unit 105, issue a command necessary for achieving respectivelythe recording, editing, and reproducing requests to the AV file systemunit 103.

[0245] (1-2-4) Commands Executed by File system Unit 102

[0246] Following are the commands supported by the file system unit 102.

[0247] The file system unit 102 receives various commands from the AVdata recording unit 110, AV data editing unit 120, AV data reproducingunit.130, and the recording/editing/reproducing control unit 105, andmanages the files in accordance with the received commands.

[0248]FIG. 21 shows a list of commands supported by the file system unit102 for the file management. The operations executed by the file systemunit 102 in response to the commands are described below.

[0249] CREATE: generate a new file on the disc, and return a fileidentification descriptor.

[0250] DELETE: delete a file from the disc. More specifically, thecommand cancels the assignment of recording areas in units of AV blocksfor deleting an AV file, and cancels the assignment of recording areasin units of sectors for deleting a non-AV file.

[0251] OPEN: obtain a file identification descriptor to access a filerecorded on the disc.

[0252] CLOSE: close an opened file.

[0253] WRITE: record a file onto the disc. More specifically, thecommand assigns recording areas in units of sectors for AV blocks fornon-AV data, and records data into the assigned sectors.

[0254] READ: read a file from the disc.

[0255] SEEK: move inside a data stream recorded on the disc.

[0256] RENAME: change a file name.

[0257] MKDIR: generate a new directory on the disc.

[0258] RMDIR: remove a directory from the disc.

[0259] STATEFS: inquire about the current state of the file system.

[0260] GET-ATTR: obtain an attribute of a file.

[0261] SET-ATTR: change an attribute of a currently opened file.

[0262] AV-WRITE: record an AV file onto the disc. More specifically, thecommand recording areas in units of AV blocks, and records data into theassigned AV blocks.

[0263] MERGE: merge two AV files on the disc into data in the memory.

[0264] SPLIT: split an AV file on the disc into two AV files.

[0265] SHORTEN: delete unnecessary part (an edge part) of an AV file onthe disc.

[0266] REPLACE: replace a part of an AV file with data in the memory.

[0267] SEARCH DISCON: detect whether a specified section includes adiscontinuous boundary (zone boundary), return “TRUE” if it includes thediscontinuous boundary; and return “FALSE” if it does not include thediscontinuous boundary.

[0268] It should be noted here that comands for recording AV data andnon-AV data are separately supported as the AV-WRITE command and theWRITE command.

[0269] The AV data recording unit 110, AV data editing unit 120, and AVdata reproducing unit 130 achieves processes such as recording, editing,and reproducing by using combinations of the above commands.

[0270] (1-3) Recording/Deleting

[0271] Now, the operations of the DVD recorder 10 is described indetail. The operations are: (1-3-1) Manual Recording of AV Data, (1-3-2)Programmed Recording of AV Data, (1-3-3) Deleting of AV Data, (1-3-4)Recording of Non-AV Data, and (1-3-5) Deleting of Non-AV Data.

[0272] (1-3-1) Manual Recording of AV Data

[0273] The manual recording is a recording immediately started when theuser presses the “Record” key on the remote controller without setting atime for a programmed recording and sets two or three items on thescreen.

[0274] For example, when the user presses the RECORD button on theremote controller 6 shown in FIG. 22, the display 12 displays a guidanceimage 200 shown in FIG. 23 under the control of therecording/editing/reproducing control unit 105. When the user presses“1” and “Selection” keys on the remote controller while the guidanceimage 200 is displayed on the screen, a guidance image 201 for settingrecording conditions (in the present example, the “recording time” and“recording quality”) is displayed.

[0275] For setting the recording time, the user first moves the focus onthe screen onto either “no limit” or “specify” by operating the cursorbutton on the remote controller 6, then presses “Selection” button.Here, if the user selects “specify,” the screen changes to a guidanceimage for urging the user to input a time by operating the ten keybuttons. After the user specifies the time, the screen returns to theguidance image 201.

[0276] The “recording quality” as a recording condition relates to thebit rate and resolution of the MPEG data and has three types: “high,”“standard,” and “time-ensuring.” The bit rate and resolution for eachquality type is shown in FIG. 24.

[0277] Here, suppose the user selects “no limit” and “timeensuring”quality on the guidance image 201, and then presses the “Record” buttonon the guidance image 202, as a sample case of the manual recording.This series of operations allows the manual recording to be started.

[0278]FIG. 25A is a flowchart showing the manual recording process.

[0279] The process starts as a notification that the user has pressedthe “Record” button is sent to the recording/editing/reproducing controlunit 105 via the user IF unit 106. On receiving the notification, thecontrol unit 105 issues the CREATE command to the common file systemunit 104 (step 250). On receiving the command, the common file systemunit 104 returns the file identification descriptor when it is possibleto create a file. In this process, the file size is specified as themaximum size of the disc since “no limit” has been specified by the useras the recording time. Also, the recording/editing/reproducing controlunit 105 sends a file identifier and a parameter indicating the“time-ensuring” quality specified as the recording condition to the AVdata recording unit 110.

[0280] The AV data recording unit 110 instructs the MPEG encoder 2 tostart encoding the video and audio data of a predetermined channelreceived through the receiver 9 and transferring the encoded MPEG datato the track buffer 3 a. While the above process is proceeding, the AVdata recording unit 110 issues the OPEN command to the AV file systemunit 103 (step 251) to allow the AV file system unit 103 to store thefile identification descriptor given by the control unit 105 andinformation on the file entry into a work memory (not illustrated) (theinformation stored in the work memory is also referred to as “Fd” (Filedescriptor).

[0281] The AV data recording unit 110 issues the AV-WRITE command to theAV file system unit 103 every time the track buffer 3 a stores apredetermined amount of MPEG data until it receives a stop command fromthe control unit 105 (steps 252 and 253). When receiving the stopcommand, the AV data recording unit 110 issues the AV-WRITE command(step 254), and issues the CLOSE command (step 255) to end the presentprocess. The AV-WRITE command is issued in step 254 to process theallocation descriptor of the last extent to be held in the Fd. The CLOSEcommand is issued in step 255 to write back the Fd in the work memoryonto the DVD-RAM disc as a file identification descriptor, a file entryor the like on the DVD-RAM disc.

[0282] Now, the data recording process executed by the AV-WRITE commandis described in detail.

[0283]FIG. 26 is a flowchart showing the process performed by the AVfile system unit 103 having received the AV-WRITE command. Here, it ispresumed that the AV-WRITE command is issued to the AV file system unit103 together with three parameters specified. The three parametersrespectively indicate: the Fd having been opened by the OPEN command asdescribed above; the size of data to be recorded; and a buffer (in thisembodiment, the track buffer 3 a) storing the data. The Fd specified bythe parameter includes, as the file entry does, information of a storageposition of an extent and a length of the extent. The Fd is updatedevery time the AV-WRITE command is issued during the period between theopening and closing of the Fd. For the second or a subsequent issue ofthe AV-WRITE command, new data is additionally written, following thealready-recorded data.

[0284] As shown in FIG. 26, the AV file system unit 103 holds a counterfor counting for a size specified as a parameter. Until data of thespecified size is completely recorded (step 265:No), the AV file systemunit 103 assigns areas to the data, one sector by one sector, andrecords the data onto the disc. More specifically, when an opened filedoes not include already-recorded data (when the AV-WRITE command isissued once in a recording process); or when an opened file includesalready-recorded data (when the AV-WRITE command is issued twice in arecording process) and the data is recorded to the end of an AV block(step 266:No), the AV file system unit 103 detects an AV block withstatus “100” (unassigned) by referring to the AV block management table(step 267), changes the status to “01” (for AV data) (step 268), andchanges the statuses of all the sectors included in the AV block from“1” (unassigned) to “0” (assigned) (step 269).

[0285] When an opened file includes already-recorded data and the datais not recorded to the end of an AV block (step 266: Yes), the AV filesystem unit 103 proceeds to step 270.

[0286] The AV file system unit 103 fetches data having a size of onesector from the track buffer 3 a, and records the fetched data to thefirst sector of the newly assigned AV block or to a sector following adata-recorded sector on the DVD-RAM disc (step 270). The AV file systemunit 103 then updates the counter (step 271). The AV file system unit103 judges whether two sectors in which data was recorded most recentlyare consecutive sectors (step 272). The AV file system unit 103 judgesthat the two sectors are not consecutive when the two sectors are notphysically consecutive or when a zone boundary exists between thesectors. The presence of a zone boundary between the sectors is judgedby referring to the last-block-length table shown in FIG. 5. When it isjudged as negative in step 272, the AV file system unit 103 allows theallocation descriptor of Fd to hold, as one extent, the AV data recordedthe AV block immediately before the current AV block (step 273). When itis judged as positive in step 272, control returns to step 265.

[0287] When data of the specified size is completely recorded byrepeating the recording of data into sectors (step 265:Yes), the AV filesystem unit 103 allows Fd to hold the allocation descriptor of the lastextent including the last-recorded sector (step 274) to end the“AV-WRITE” process.

[0288] As described above, on receiving the AV-WRITE command, the AVfile system unit 103 assigns areas to the specified AV data in units ofAV blocks which are each a consecutive area of about 7 MB. With thisarrangement, each extent, except the last extent, in each AV file inwhich AV data has been recorded has at least about 7 MB. This ensuresthe uninterrupted reproduction.

[0289] It is described for the sake of conveniences that data having asize of one sector is recorded onto the DVD-RAM disc in step 270.However, in reality, data is recorded onto the DVD-RAM disc each timethe track buffer stores data equivalent to one ECC block (16 sectors) insize. (1-3-2) Programmed Recording of AV Data

[0290] The programmed recording is a recording process performed whenthe user presses the “Record” key on the remote controller with a timefor programmed recording set.

[0291] Here, it is presumed that the user selects “Specify” and“Time-Ensuring” on the guidance image 201, as a sample case of theprogrammed recording. This allows the programmed recording to bestarted.

[0292]FIG. 25B is a flowchart showing the programmed recording process.

[0293] The process starts as a notification that the user has pressedthe “Record” button is sent to the recording/editing/reproducing controlunit 105 via the user IF unit 106. On receiving the notification, thecontrol unit 105 notifies the common file system unit 104 of thespecified time and issues the CREATE command to the same unit 104 (step256). On receiving the command, the common file system unit 104 returnsthe file identification descriptor when it is possible to create a file.In this process, the file size is specified to be the number of AVblocks corresponding to the specified time. Also, therecording/editing/reproducing control unit 105 judges whether areascorresponding to the specified time can be assigned based on whether afile identification descriptor has been sent (step 257).

[0294] Having judged that the areas cannot be assigned, the control unit105 ends the programmed recording process by performing the errorprocess.

[0295] Having judged that the areas can be assigned, the control unit105 sends a file identifier. A specified time, and a parameterindicating the “time-ensuring” quality specified as the recordingcondition to the AV data recording unit 110. On receiving these types ofinformation, the AV data recording unit 110 issues the OPEN command(step 259) when it is the specified time to start recording (step 258).The subsequent processes of the AV data recording unit 110 are almostthe same as the steps 252-255 shown in FIG. 25A: issuing the OPENcommand to the AV file system unit 103, repeating to issue the AV-WRITEcommand until it is the end time, and issuing the CLOSE command (steps258-262).

[0296] As described above, the programmed recording starts afterchecking whether enough unassigned AV blocks for the specified time areavailable for the programmed recording.

[0297] Note that the order of the steps 256 and 257 may be reversed.

[0298] (1-3-3) Deleting of AV Data

[0299] Both AV files and non-AV files are deleted by the common filesystem unit 104 when the DELETE command is issued: When receiving theDELETE command to delete a certain file, the common file system unit 104judges whether the certain file is an AV file or a non-AV file byreferring to the extension of the file name and attribute information.The common file system unit 104 performs different processes on the AVblock management table and the space bit map in accordance with theabove judgement result.

[0300]FIG. 27 is a flowchart showing the process of deleting AV filesperformed by the common file system unit 104.

[0301] The common file system unit 104 judges whether an extent shouldbe deleted by referring to the file entry of the specified AV file (step240). Having judged as positive in this step, the common file systemunit 104 updates the AV block management table by changing the status ofthe AV block included in the extent from “01” (for AV data) to “00”(unassigned) (step 241), updates the space bit map by changing thestatuses of all the sectors included in the AV block from “0” (assigned)to “1” (unassigned) (step 242), and deletes the extent from file entry(step 243). When there is no extent to be deleted (step 240:No), thecommon file system unit 104 deletes the file identification descriptorand ends the AV file deletion process.

[0302]FIG. 28A shows deleted AV files. The upper part of the drawingshows that AV files #1 and #2 are recorded in the AV blocks #10 to #14.The AV file #1 is composed of two extents (AV files #1-1 and #1-2). TheAV file #2 is composed of AV files #2-1 and #2-2. The lower part of FIG.28A shows that extents have been deleted from the AV file #1 of the AVblocks #11 and #14.

[0303]FIG. 28B shows the changes in the AV block management table andthe space bit map corresponding to the deletion shown in FIG. 28A. Theleft-hand side of FIG. 28B shows the state before deletion, and theright-hand side shows after deletion. In the AV block management table,statuses of the AV blocks #11 and #14 are changed from “01” (for AVdata) to “00” (unassigned) in accordance with the procedure shown inFIG. 27. In the space bit map, statuses of all the sectors included inthe AV blocks are changed from “0” (assigned) to “1” (unassigned). Itshould be noted here that the lower part of FIG. 28A is not intended toshow that the AV data included in the AV blocks #11 and #14 isphysically deleted. In reality, the AV data is dealt with as invaliddata by the AV file system unit 103.

[0304] (1-3-4) Recording of Non-AV Data

[0305]FIG. 29 is a flowchart showing the process of recording non-AVfiles performed by the common file system unit 104.

[0306] The common file system unit 104

[0307] On receiving the WRITE command from therecording/editing/reproducing control unit 105, the common file systemunit 104 judges whether there is non-AV data to be recorded (step 261).Having judged as positive in this step, the common file system unit 104detects unassigned sectors which are written as “1” (unassigned) in thespace bit map and are included in the AV blocks written as “10” (fornon-AV) or “00” (unassigned) in the AV block management table (step262). When the status of the AV block including the detected sectors is“00” (unassigned), the common file system unit 104 changes the status to“10” (for non-AV) (step 263), changes the statuses of the detectedsectors from “0” (assigned) to “1” (unassigned) (step 264), and recordsthe non-AV data into the detected sectors (step 265). The common filesystem unit 104 then judges whether two sectors in which data wasrecorded most recently are consecutive (step 266). When it is judged aspotive in step 266, control returns to step 261; when it is judged asnegative, the common file system unit 104 records into the file enty theallocation descriptor of the extent including the sector immediatelybefore the current sector (step 268) to end the non-AV data recordingprocess.

[0308] (1-3-5) Deleting of Non-AV Data

[0309] On receiving the DELETE command specifying a certain file fromthe recording/editing/reproducing control unit 105, and when the certainfile is non-AV file, the common file system unit 104 performs thedeletion process as follows.

[0310]FIG. 30 is a flowchart showing the process of deleting non-AVfiles performed by the common file system unit 104.

[0311] The common file system unit 104 judges whether an extent shouldbe deleted by referring to the file entry of the specified non-AV file(step 271). Having judged as positive in this step, the common filesystem unit 104 updates the space bit map by changing the statuses ofall the sectors included in the extent from “0” (assigned) to “1”(unassigned) (step 272).

[0312] The common file system unit 104 then judges whether the statusesof all the sectors included in an AV block in the extent are “1”(unassigned) by referring to the AV block management table (step 273).When it is judged so in the step, the common file system unit 104updates the AV block management table by changing the status of the AVblock from “10” (for non-AV data) to “00” (unassigned) (step 274). Thecommon file system unit 104 deletes the allocation descriptor of theextent from the file entry (step 275), then returns to step 271. When itis judged that there is no extent to be deleted, the non-AV filedeletion process ends.

[0313]FIG. 31A shows deleted non-AV files. The upper part of the drawingshows that AV block #11 includes non-AV files #3 and #4. Each of thenon-AV files #3 and #4 includes only one extent. The lower part of FIG.31A shows that the extent has been deleted from the non-AV file #3.

[0314]FIG. 31B shows the changes in the AV block management table andthe space bit map corresponding to the deletion shown in FIG. 31A. Theleft-hand side of FIG. 31B shows the state before deletion, and theright-hand side shows after deletion. In the AV block management table,the status of the AV block #11 remains to be “10” (for non-AV data) inaccordance with the procedure shown in FIG. 30 since file #4 remains inthe block. In the space bit map, statuses of all the sectors included inthe extent of AV block #11 are changed from “0” (assigned) to “1”(unassigned). It should be noted here that the lower part of FIG. 31A isnot intended to show that the non-AV data included in the file #3 isphysically deleted. In reality, the non-AV data is dealt with as invaliddata by the AV file system unit 103.

[0315] As apparent from the above description, the DVD-RAM of thepresent embodiment includes the space bit map and the AV blockmanagement table as a part of the file system management information.This construction ensures uninterrupted reproduction of AV data sinceconsecutive areas are assigned in units of AV blocks.

[0316] In the DVD-RAM of the present embodiment, when an AV block isassigned to AV data, the statuses of all the sectors included in the AVblock are changed to “assigned” in the space bit map. With such amanagement method, even if the DVD-RAM of the present invention isaccessed by a conventional file system which supports only the space bitmap, the following problems are prevented: data is written into sectorsincluded in AV blocks for AV data, and consecutive sector areas assignedto AV data are used and lost.

[0317] Concerning the sectors included in AV blocks assigned to non-AVdata, only the statuses of the sectors in which data has actually beenrecorded are shown as “assigned” in the space bit map. That is to say,different from the case of the AV blocks assigned to AV data, thestatuses of the sectors in which data has not been recorded are notshown as “assigned” in the space bit map.

[0318] With the above construction, non-AV data can be recorded into anAV block when there are unassigned areas in it even if the AV block hasalready been assigned to another kind of non-AV data. This enables theuse efficiency of the entire disc to be improved even if the discincludes both AV blocks for AV data and AV blocks for non-AV data.

[0319] In the above embodiment, the DVD recorder 10 is, as shown in FIG.14, constructed based on the premise that it is used as a replacementfor a VTR used at home. Not limited to the construction, when theDVD-RAM disc is to be used as a recording medium for computers, thefollowing constructions are possible. That is to say, the disc accessunit 3 is connected, as a DVD-RAM drive apparatus, to a computer bus viaan IF called SCSI or IDE. Also, the components other than the discaccess unit 3 shown in FIG. 15 are achieved or operated when the OS andthe application program are executed on the computer hardware. In thiscase, the disc recording unit 100, disc reading unit 101, and filesystem unit 102 are mainly achieved as applications for enhancing the OSor the functions of the OS. Also, the other components other than theseare mainly achieved as functions of the application programs. Thevarious commands supported by the file system unit 102 are equivalent toservice commands, such as a system call command, provided to theapplications.

[0320] In the above embodiment, two bits are used to indicate theassignment status of each piece of AV data in the AV block managementtable. However, the number of bits may be increased so that other kindsof attribute information can be added.

[0321]FIG. 32 shows the second construction example of the AV blockmanagement table.

[0322] The AV block management table includes an arrangement of aplurality of pieces of two-byte data which each shows the assignmentinformation and attribute information. The upper four bits of each pieceof two-byte data are used for representing the assignment status of theAV blocks as described in the present embodiment. The lower 12 bitsrepresent the number of effective ECC blocks in the corresponding AVblock. For example, the first AV block includes 224 (“E₀” in hexadecimalnotation) effective ECC blocks, and the sixth AV block includes 223(“DF” in hexadecimal notation) effective ECC blocks.

[0323] As described above, in the AV block management table shown inFIG. 32, the number of effective ECC blocks for each AV block isrecorded, the number of effective ECC blocks being the total number ofECC blocks included in each AV block from which the number of ECC blocksincluding an address error is subtracted. If the file system unit 102could not obtain the number of effective ECC blocks, the file systemunit 102 would be required to perform an address error process whenrecording data since it is impossible for the file system unit 102 torecognize the amount of data that can be recorded into each AV blockwithout the information. According to the AV block management tableshown in the drawing, the file system unit 102 is relieved from thecomplicated address error process necessary when data is recorded.

[0324] Note that it is also possible to have another information whichindicates the ECC blocks or sectors in which address errors occur and toallow the AV file system to use the information.

[0325] It is also possible to reduce the amount of process performed bythe file system by using the most significant bit as a flag indicating“variable length” or “not-variable length” and by using the valueindicating the size of the AV block as an effective value only when theflag is on. This is possible when the probability of the occurrence ofaddress errors is very low and when almost all the AV blocks arerecognized as having a fixed length.

[0326]FIG. 33 shows the third construction example of the AV blockmanagement table.

[0327] The AV block management table includes an arrangement of aplurality of pieces of four-bit data which each shows the assignmentinformation and attribute information. The lower three bits of eachpiece of four-bit data are used for representing the assignment statusof the AV blocks as described in the present embodiment. When the mostsignificant bit is “1” (also referred to as a variable-length bit) thebit indicates that the current AV block has a variable length, when thebit is “0” the bit indicates a fixed length. Here, when an AV block hasa fixed length, it indicates that the AV block includes 224 effectiveECC blocks without address errors. Otherwise, the AV block has avariable length. An AV blocks has a variable length when the AV blockincludes an ECC block having an address error or when the AV block isthe last AV block adjacent to a zone boundary.

[0328] The block length of a variable AV block is recorded in thevariable-length AV block table shown on the right-hand side of thedrawing. The table, replacing the last block-length table shown in FIG.5, includes, for each variable AV block, a block number and the numberof effective ECC blocks. As shown in the drawing, in the AV blockmanagement table, AV blocks with the variable-length bit are representedby boxes with slant lines. The number of effective ECC blocks for eachof these variable-length AV blocks is recorded in the variable-length AVblock table. With such an arrangement in which the variable-length AVblock table includes, for each variable AV block, a block number and thenumber of effective ECC blocks, it is possible for the file system torefer to the variable-length AV block table using the AV block numberwhen managing the AV blocks with variable-length flag in the AV blockmanagement table. Also, the third construction example, compared withthe second construction example, has a reduced size of the AV blockmanagement table.

[0329] When the physical size of each AV block is set asvariable-length, it is possible to perform the mapping of the sectorsand the AV blocks without difficulty by recording the sizes of all theAV blocks in the variable-length AV block table. it is further possibleto perform the mapping of the sectors and the AV blocks withoutdifficulty by recording the start sector number, track number, zonenumber in the AV block management table, instead of recording thephysical sizes of AV blocks in the variable-length AV block table.

[0330]FIG. 34 shows the fourth construction example of the AV blockmanagement table.

[0331] The AV block management table includes an arrangement of aplurality of pieces of two-byte data which each correspond to one AVblock. Each piece of two-byte data indicates the number of filesrecorded in the AV block, as well as the assignment status. The upperfour bits are used for representing the assignment status of the AVblocks as described in the present embodiment. The lower 12 bitsindicate the number of files. Here, the number of files is 4095 at themaximum. Therefore, it is possible to record 4095 files in one AV block.

[0332] Here, the lower 12 bits are referred to as a counter. Eachcounter corresponds to one AV block. It may happen that one file isdivided and recorded in a plurality of AV blocks when the file is AVfile generally having a large size or due to the area assignment even incase of a non-AV file generally having a small size. In this case, thecounter regards a part of a file recorded in the AV file as one file.That is to say, whether the AV file includes a whole file or a part of afile, each case is recognized as one file by the counter. Also, when afile is divided and recorded in a plurality of extents in one AV block,the file is regarded as one file.

[0333] The use of such a counter provides two merits to the managementof the AV blocks. The first merit is that it becomes easier to judgewhether to release AV blocks for non-AV data. In the present embodiment,the file system unit 102 releases an AV block as unassigned whenconfirming by referring to the space bit map that all the sectorsincluded in the AV block are unassigned. As understood from this, in thepresent embodiment, to release an AV block, the space bit map isreferred to. However, when the AV block management table includescounters as shown in FIG. 34, it is possible to release an AV block fornon-AV data when the counter is “0.” This eliminates the necessity forreferring to the space bit map. It is needless to say that the space bitmap should be updated each time data is deleted from any sectors.

[0334] The second merit is that it becomes easier for a plurality offiles to coexist in one AV block for AV data. The term “coexist”indicates a case in which one AV file is divided into a plurality of AVfiles by editing not that an AV file is added to an AV block in whichanother AV file has already been recorded. In this case, it is possibleby using the counter to detect the presence of a plurality of AV filesin an AV block and to release an AV block when the counter is “0.”

[0335] In reality, it is enough to take into account a case where twofiles coexist in one AV block. In this case, it is enough to set a flag,instead of a counter, indicating “coexist” of “not coexist.” In thiscase, the file system unit 102 may refer to the space bit map todetermine whether to release an AV block for non-AV data, as describedin the present embodiment, and may refer to the “coexistent” flag todetermine whether to release an AV block for AV data.

[0336] It is also possible for the fourth construction example to usethe variable-length bit described in the third construction example.Furthermore, it will also be possible for the AV block management tableto additionally include the size of AV block if the size of the data foreach AV block is increased to three bytes or more.

[0337]FIG. 35 shows the fifth construction example of the AV blockmanagement table.

[0338] In the present embodiment, the last AV block in each zone has avariable length so as not a zone boundary is within one AV block. In thefifth construction example, each AV block has a fixed length of about 7MB, and AV blocks are arranged from the start of the disc in order. Inthis case, like the AV blocks represented by slant lines in FIG. 35,some AV blocks may include a zone boundary. It is impossible to securethe uninterrupted reproduction for the AV blocks including a zoneboundary. Therefore, it is required to manage the information indicatingwhether each AV block includes a zone boundary. For this purpose, thefifth construction example allows the AV block management table to havea flag indicating whether each AV block includes a zone boundary.

[0339] The AV block management table shown in FIG. 35 includes anarrangement of a plurality of pieces of four-bit data which eachcorrespond to one AV block. The upper one bit indicates whether thecorresponding AV block includes a zone boundary. The lower three bitsindicate the assignment status of the AV block. In this case, the filesystem unit 102 assigns three consecutive AV blocks whose center AVblock having a zone boundary to one AV file, and does not assign one AVblock having a zone boundary to one AV file. With this arrangement, itis possible to ensure the uninterrupted reproduction even if an AV fileis recorded into the AV block having a zone boundary.

[0340] When it is presumed that only non-AV files can be recorded in theAV blocks including a zone boundary, the same number of AV blocks as thenumber of zone boundaries, that is 24 AV blocks should be prepared forthe non-AV files. The total capacity of the 24 AV blocks amounts to 164MB. That means, the capacity of the area in which AV files can berecorded reduces. As a result, it is desirable for the file system unit102 to manage the above-described three consecutive AV blocks togetherfor each zone boundary.

[0341] It is also possible for the AV block management table shown inFIG. 6 to include a discontinuous flag which indicates that the AVblocks before and after a zone boundary are not consecutive. With thisarrangement, it will be easier for the file system unit 102, whenassigning two consecutive AV blocks, to judge whether the twoconsecutive AV blocks have a zone boundary in between since the unit 102can obtain the information by referring to the AV block managementtable.

[0342] When a set of AV blocks for non-AV data is reserved in advance,with the set having a predetermined size, the mixed presence of the AVblocks for AV data and non-AV data is prevented. This makes it easier toassign consecutive areas to AV data.

[0343] When a disc having been written by an AV file system is notcompatible with discs having been written by another type of filesystem, and when the disc is accessed only by the AV file system, it ispossible to write as “assigned” the statuses of the sectors in which AVdata has actually been recorded, not the statuses of all the sectorsincluded in AV blocks whose statuses are written as “for AV data.” Thismakes it easier to manage the unassigned areas in the AV blocks.

[0344] In the present embodiment, the statuses of all the sectorsincluded in an AV block for AV data are written as “assigned.” However,only the statuses of the sectors in which AV data has actually beenrecorded may be written as “assigned.” This makes it easier to managethe unassigned areas in the AV blocks though compatibility between discshaving been written by the AV file system and another type of filesystem is somewhat lost.

[0345] (2) Embodiment 2

[0346] Now, the optical disc and the optical disc recording/reproducingapparatus of Embodiment 2 are described.

[0347] (2-1) Optical Disc

[0348] Embodiment 2 differs from Embodiment 1 in that (1) pseudoconsecutive records, instead of the AV blocks, are assigned to AV datato be recorded, and that (2) pseudo consecutive record assignmentmanagement information is used instead of the AV block management table.The differences (1) and (2) are described below in detail.

[0349] With regard to the above difference (1), in Embodiment 1, theentire data recording area is almost fixedly divided into AV blocks eachwith a fixed length in advance whether AV data has been recorded or notin the area. In contrast, in Embodiment 2, AV blocks are not used.Instead, areas called pseudo consecutive records are dynamicallyassigned to AV data, each pseudo consecutive record having a sizegreater than the fixed length described in Embodiment 1.

[0350] With regard to the above difference (2), in Embodiment 1, one AVblock management table is used to manage the assignment states of allthe AV blocks. In contrast, in Embodiment 2, the pseudo consecutiverecord assignment management information for managing the pseudoconsecutive record is recorded on the disc for each AV file.

[0351] Accordingly, FIGS. 1-3 and 8-12 used in Embodiment 1 also applyto the optical disc of Embodiment 2. FIG. 4 can also be applied toEmbodiment 2 by deleting the AV blocks. Since in Embodiment 2, the othercharacteristics are the same as Embodiment 1: the partition region isdivided into a plurality of zone areas; and reading and writing of dataare performed in units of ECC blocks (each having 16 sectors). Also,although the AV management table shown in FIG. 6 is not used inEmbodiment 2, the sector management table (space bit map) is used aswell.

[0352] (2-1-1) Pseudo Consecutive Record

[0353] Each AV file in the present Embodiment is composed of one or morepseudo consecutive records to ensure the uninterrupted reproduction. The“pseudo consecutive record” is defined as an area recording AV data orthe AV data recorded in the area, where the AV data may be whole orpartial, has a size greater than a size that ensures a consecutivereproduction, and the area is composed of consecutive sectors or ECCblocks. However, the skipping by the ECC block skip method is counted infor the consecutive sectors or ECC blocks.

[0354] According to the ECC block skip method, when a defective sectorwhich causes an address error or the like is detected, the ECC blockincluding the defective sector is skipped and data is written into thenext ECC block. This method is more suitable for the consecutivereproduction of AV data than the linear replacement method in which whena similar defect sector is detected, data is written into a sector in areplacement area having been reserved in the same zone. This is becausea jump to the replacement area does not occur in case of the ECC blockskip method.

[0355] Each pseudo consecutive record includes ECC blocks the number ofwhich is represented by any integer. The start sector of each pseudoconsecutive record is the start sector of one of the ECC blocks. That isto say, each pseudo consecutive record is located within a single zone.The minimum size of the pseudo consecutive record is set to 224 ECCblocks (about 7 MB) to ensure the consecutive reproduction of AV data,as in the AV block in Embodiment 1.

[0356] The pseudo consecutive record assignment management informationshowing an assignment result of a pseudo consecutive record is generatedand recorded for each AV file. The pseudo consecutive record assignmentmanagement information may be recorded in the start of the correspondingAV file. However, in the present embodiment, the information is recordedas non-AV files respectively corresponding to the AV files. The pseudoconsecutive record assignment management information has a liststructure.

[0357] (2-1-2) Assignment of Pseudo Consecutive Records

[0358] Each piece of pseudo consecutive record assignment managementinformation (also referred to as management information) corresponds toan AV file and shows areas on the disc which are assigned as pseudoconsecutive records to the current AV file.

[0359] The optical disc recording apparatus assigns unassigned areas onthe optical disc as pseudo consecutive records to AV files prior torecording of the AV files.

[0360]FIG. 36A shows a specific example of the management information.FIG. 36B shows a space bit map corresponding to the managementinformation shown in FIG. 36A.

[0361] In FIG. 36A, the management information is described as a tableincluding entries el and e2. Each entry includes, from left to right inthe drawing, a start sector number (LSN: Logical Sector Number), an endsector number, and an attribute. Attribute “0” indicates a pseudoconsecutive record; attribute “1” indicates an unassigned area. In thepresent example, the attribute is always “0.”

[0362] The area identified by the start and end sector numbers specifiedby each entry indicates a series of sectors which has been assigned as awhole or a partial pseudo consecutive record.

[0363] Here, a relationship between the pseudo consecutive record andthe extent which is managed in the file system is described. The pseudoconsecutive records and the extents correspond to each other in aone-to-one relation when the extent does not outstep a zone boundary; aplurality of pseudo consecutive records correspond to one extent whenthe extent outsteps a zone boundary. For example, when an extentoutsteps a zone boundary, two pseudo consecutive records are formedbefore and after the zone boundary, both corresponding to the extent.

[0364] (2-1-3) Pseudo Consecutive Record Assignment ManagementInformation and Space Bit Map

[0365]FIG. 36B shows a space bit map corresponding to the managementinformation shown in FIG. 36A. In the example shown in the drawing, bitscorresponding to sectors (sector numbers 6848-15983) of pseudoconsecutive area #1 are all “0” indicating “assigned.” It is desirablethat the management information and the space bit map are managedtogether so that they reflect each other, although they use differentunits to indicate the assignment states of the data area. The opticaldisc recording apparatus sets the bits in the space bit mapcorresponding to sectors assigned as pseudo consecutive areas to “0”indicating “assigned.”

[0366] (2-2) Recording/Reproducing Apparatus

[0367] Here, the optical disc recording/reproducing apparatus ofEmbodiment 2 is explained.

[0368] (2-2-1) System and Hardware Structure

[0369] Embodiment 2 uses the same structures as Embodiment 1 in terms ofthe system structure shown in FIG. 14, the hardware structure of the DVDrecorder shown in FIG. 15, the structure of MPEG encoder 2 shown in FIG.16, and the structure of MPEG decoder 4 shown in FIG. 17.

[0370] Embodiment 2 differs from Embodiment 1 in that (1) pseudoconsecutive records, instead of the AV blocks, are assigned to AV datato be recorded, and that (2) pseudo consecutive record assignmentmanagement information is used instead of the AV block management table.Accordingly, a program different from the program is stored in the mainmemory 1 d shown in FIG. 15 for use in the present embodiment.

[0371] (2-2-2) Function Block Diagram

[0372]FIG. 37 is a function block diagram showing the construction ofthe DVD recorder 10 of Embodiment 2 based on the functions of thecomponents. Each function shown in the figure is achieved after the CPU1 a in the control unit 1 executes the program in the main memory 1 d tocontrol the hardware shown in FIG. 14.

[0373] In FIG. 37, reference numerals similarly numbered as those inFIG. 18 for Embodiment 1 designate like components, and a recounting oftheir function will be omitted from the description of this embodiment.

[0374] Embodiment 2 differs from Embodiment 1 in that the file systemunit 102, recording/editing/reproducing/control unit 105, and AV datarecording unit 110 shown in FIG. 18 are not used, but a file system unit202, recording/editing/reproducing/control unit 205, and AV datarecording unit 210 are used instead.

[0375] The file system unit 202 differs from the counterpart inEmbodiment 1 in that it includes an AV file system unit 203 and a commonfile system unit 204 instead of the AV file system unit 103 and a commonfile system unit 104.

[0376] The AV file system unit 203 differs from the AV file system unit103 only in that it does not support the AV_WRITE command shown in FIG.21.

[0377] The common file system unit 204 differs from the common filesystem unit 104 only in that the WRITE command is used to write AV dataas well as non-AV data onto the disc. That is, the file system unit 202does not discriminate between AV data and non-AV data, but deals withthem equally. The AV data and non-AV data are treated differently by theAV data recording unit 210, AV data editing unit 220, and AV datareproducing unit 230.

[0378] The AV data recording unit 210, AV data editing unit 220, and AVdata reproducing unit 230, respectively on receiving a recordingrequest, an editing request, and a reproducing request from therecording/editing/reproducing/control unit 205, issues necessarycommands to the AV file system unit 103.

[0379] The AV data recording unit 210, on receiving a recording requestfrom the control unit 205, issues a command necessary for the requestedrecording to the AV file system unit 103, and also creates or updatesthe management information shown in FIG. 36A. More specifically, the AVdata recording unit 210, on receiving a recording request, searches forunassigned areas by referring to the space bit map and the managementinformation, assigns an area having a size greater than theearlier-mentioned fixed length of about 7 MB, and also creates a newpiece of management information shown in FIG. 36A. Here, when a pseudoconsecutive record has already been created, it is desirable that anarea following or as close as possible to the existent pseudoconsecutive record is assigned as a new pseudo consecutive record. TheAV data recording unit 210 then creates a new piece of managementinformation for the newly assigned area.

[0380] (2-3-1) Recording of AV Files

[0381] Recording of AV files in the DVD recorder 10 is described indetail.

[0382]FIG. 38 is a flowchart showing the recording process in the DVDrecorder of the present embodiment.

[0383] When the user presses the RECORD button or when the “currenttime” reaches the start time of “programmed recording,” a notificationof recording start is sent to the recording/editing/reproducing/controlunit 105 via the user IF unit 106.

[0384] On receiving the notification, the control unit 105 assigns anarea having a size greater than the predetermined size (about 7 MB) as apseudo consecutive record (step 380). More specifically, the controlunit 105 refers to the space bit map and the management information todetect unassigned consecutive sector areas. The control unit 105 thenassigns the detected unassigned consecutive sector areas as a new pseudoconsecutive record. In doing so, when other AV data has already beenrecorded in the disc and when the AV data to be recorded continues fromthe existent AV data logically, the control unit 105 assigns aconsecutive recording area that continues from the already-assignedconsecutive recording area of the existent AV data, if it is possible.

[0385] The recording/editing/reproducing control unit 105 sends a fileidentifier and a parameter indicating the “time-ensuring” qualityspecified as the recording condition to the AV data recording unit 210.The AV data recording unit 210 instructs the MPEG encoder 2 to startencoding the video and audio data of a predetermined channel receivedthrough the receiver 9 and transferring the encoded MPEG data to thetrack buffer 3 a (step 381).

[0386] The recording/editing/reproducing control unit 105 issues theCREATE command specifying the newly assigned pseudo consecutive recordto the common file system unit 204 (step 382). On receiving the command,the common file system unit 204 returns a new file identificationdescriptor when it is possible to create a file in the newly assignedpseudo consecutive record.

[0387] After the above process, the AV data recording unit 210 issuesthe OPEN command to the AV file system unit 203 (step 383) to allow theAV file system unit 203 to store the file identification descriptorgiven by the control unit 105 and information on the file entry into awork memory (not illustrated) (the information stored in the work memoryis also referred to as “Fd” (File descriptor).

[0388] The AV data recording unit 210 issues the WRITE command to the AVfile system unit 203 every time the track buffer 3 a stores apredetermined amount of MPEG data (steps 385 and 386). The AV datarecording unit 210 continues to perform this process until it receives astop instruction from the control unit 105 (step 384:Yes). Here, it ispresumed that the WRITE command is issued to the system unit 203together with three parameters specified. The three parametersrespectively indicate: the Fd having been opened by the OPEN command asdescribed above; the size of data to be recorded; and a buffer (in thisembodiment, the track buffer 3 a) storing the data.

[0389] The Fd specified by the parameter includes, as the file entrydoes, information of a storage position of an extent and a length of theextent. The information represents the pseudo consecutive recordassigned in the step 380. The Fd is updated every time the WRITE commandis issued during the period between the opening and closing of the Fd.For the second or a subsequent issue of the WRITE command, new data isadditionally written, following the already-recorded data.

[0390] On receiving the stop instruction (step 384), the AV datarecording unit 210 issues the WRITE command (step 387). The AV datarecording unit 210 then issues the CLOSE command (step 388). The AV datarecording unit 210 further informs the AV file management informationgenerating unit 112 that a recording of an AV file (VOB) has ended (step389). The AV data recording unit 210 then refers to the Fd (extent) ofthe recorded AV data to create or update the management information(step 390). That is, the AV data recording unit 210 creates a new pieceof management information when an AV file is recorded for the firsttime; the AV data recording unit 210 updates the management informationand the space bit map when an AV file is additionally recorded. Thecreated or updated management information is recorded into the disc as anon-AV file via the common file system unit 204.

[0391] It should be noted here that the WRITE command is issued in step387 to record onto the disc the rest of the data in the track buffer.Also, the CLOSE command issued in step 255 is a command used to writeback the Fd in the work memory onto the DVD-RAM disc as a fileidentification descriptor, a file entry or the like on the DVD-RAM disc.

[0392] As apparent from the above description, when recording AV data,the DVD recorder of the present embodiment dynamically assigns areas aspseudo consecutive records by referring to the space bit map and themanagement information. As a result, compared with the DVD recorder ofEmbodiment 1, the DVD recorder of the present embodiment can use thedata area on the optical disc more effectively since the data area doesnot include AV blocks which are logically divided sections.

[0393] (3) Embodiment 3

[0394] Embodiment 3 differs from Embodiment 2 in that (1) the minimumsize of the pseudo consecutive record can be dynamically changed, and(2) the pseudo consecutive record assignment management information isnot used. The differences are described as follows.

[0395] With regard to the above difference (1), the DVD recorder 10 ofthe present embodiment determines the minimum size of the pseudoconsecutive record in accordance with the bit rate of a video object tobe encoded actually, while in Embodiment 2, the minimum size of thepseudo consecutive record is set to a fixed length of about 7 MB toensure the consecutive reproduction of AV data.

[0396] With regard to the above difference (2), the DVD recorder 10 ofthe present embodiment does not use the management information. Instead,the DVD recorder 10 searches for unassigned areas by referring to thespace bit map to assign areas as pseudo consecutive records to AV datato be recorded.

[0397] (3-1) Minimum Size of Pseudo Consecutive Record

[0398] First, the reason for determining the minimum size of the pseudoconsecutive record as mentioned in the above difference (1) isexplained.

[0399]FIG. 39 shows a model of buffering of AV data into the trackbuffer, the AV data being read from the DVD-RAM disc by a reproductionapparatus reproducing a video object. This model is created based onminimum specifications required for the reproduction apparatus. As faras these specifications are satisfied, the uninterrupted reproduction isensured.

[0400] In the upper part of FIG. 39, the AV data read from the DVD-RAMdisc is subjected to the ECC process. The processed AV data is thentemporarily stored in the track buffer (FIFO memory), and is sent to thedecoder. In the drawing, “TVr” represents an input transfer rate of thetrack buffer (rate of data read from an optical disc), and “Vo”represents an output transfer rate of the track buffer (decoder inputrate), where Vr>Vo. In this model, Vr=11 Mbps.

[0401] The lower part of FIG. 39 is a graph showing the change in thedata amount of the track buffer in this model. In the graph, thevertical axis represents the data amount of the track buffer; thehorizontal axis represents time. The graph is based on the premise thata pseudo consecutive record #j that has no defective sectors and apseudo consecutive record #k that has a defective sector are read in theorder.

[0402] The “T1” represents a time taken for reading out the entire AVdata recorded in the pseudo consecutive record #j that has no defectivesectors. In this period T1, the data amount of the track bufferincreases at the rate of (Vr−Vo).

[0403] The “T2” (also referred to as a jump period) represents a timetaken by the optical pickup for jumping from the pseudo consecutiverecord #j to #k. The jump period includes the seek time of the opticalpickup and the time required for the rotation of the optical disc to bestabilized. The maximum jump period is equal to the time taken forjumping from the innermost circuit to the outermost circuit. In thismodel, it is presumed that the maximum jump period is about 1500 mS. Inthis period T2, the data amount of the track buffer decreases at therate of Vo.

[0404] A period including three periods “T3” to “T5” represents a timetaken for reading out the entire AV data recorded in the pseudoconsecutive record #k that has a defective sector.

[0405] Among these periods T3 to T5, the period T4 represents a timetaken for skipping the current ECC block that has a defective sector andmoving to the next ECC block. The skipping to the next ECC block isperformed when even one defective sector is found in the current ECCblock (16 sectors). That means, when a defective sector is found, theproblem of the defective sector is solved by not using the whole ECCblock (all 16 sectors) including the defective sector, not by logicallyreplacing the defective sector by a replacement sector (replacement ECCblock). This method is called ECC block skip method which has beendescribed earlier. The period T4 represents a disc rotation wait time,where the maximum disc rotation wait time is equal to one completerotation time of the disc. In this model, it is presumed that themaximum disc rotation wait time is about 105 mS. In the periods T3 andT5, the data amount of the track buffer increases at the rate of(Vr−Vo). In the periods T4, the data amount decreases at the rate of Vo.

[0406] The size of the pseudo consecutive record is represented as“N_ecc*16*8*2048,” where the “N_ecc” represents the total number of ECCblocks included in the pseudo consecutive record. The smallest value ofN_ecc, namely the minimum size of the pseudo consecutive record iscalculated through the following procedure.

[0407] In the period T2, AV data is read from the track buffer. Onlythis is performed. If the buffer capacity becomes 0 during this period,an underflow occurs to the decoder. When this happens, the uninterruptedreproduction of the AV data cannot be ensured. Here, to ensure theuninterrupted reproduction of the AV data (not to generate theunderflow), the following formula need be satisfied.

[0408] <Formula 6>

(storage amount B)≧(consumption amount R)

[0409] The storage amount B is the amount of data that has beenaccumulated in the track buffer at the end of the period T1. Theconsumption amount R is the total amount of data read during the periodT2.

[0410] The storage amount B is calculated using the following formula.

[0411] <Formula 7>

(storage amount B)=(period T1)*(Vr−Vo)

=(read out time of one pseudo consecutive record)*(Vr−Vo)

=(L/Vr)*(Vr−Vo)

=(N _(—) ecc*16*8*2048/Vr)*(Vr−Vo)

=(N _(—) ecc*16*8*2048)*(1−Vo/Vr)

[0412] In this formula, “L” represents the size of the pseudoconsecutive record.

[0413] The consumption amount R is calculated using the followingformula.

[0414] <Formula 8>

(consumption amount R)=T2*Vo

[0415] Replacing both sides of the Formula 6 respectively by Formula 7and Formula 8 gives us the following formula.

[0416] <Formula 9>

(N_(—) ecc*16*8*2048)*(1−Vo/Vr)≧T2*Vo

[0417] From the Formula 9, it is derived that “N_ecc” representing thetotal number of ECC blocks included in the pseudo consecutive recordshould satisfy the following formula to ensure the uninterruptedreproduction of the AV data.

[0418] <Formula 10>

N _(—) ecc≧Vo*Tj/((16*8*2048)*(1−Vo/Vr))

[0419] In this formula, “Tj” represents the jump period that has beendescribed earlier. The maximum jump period is about 1.5 seconds. “Vr” isa fixed value (In the reproduction apparatus model shown in the upperpart of FIG. 39, Vr=11 Mbps). Also, considering that the video object isrepresented by a variable bit rate, “Vo” is obtained from the followingFormula 11. That is, “Vo” is obtained from Formula 11 not as the maximumvalue of the physical transfer rate of the track buffer output, but as asubstantial decoder input rate for AV data represented by a variable bitrate. In Formula 11, concerning the pseudo consecutive record length,N_pack is the total number of packs included in the video object thatshould be recorded in N_ecc ECC blocks.

[0420] <Formula 11>

Vo=(pseudo consecutive record length(bits))* (1/reproduction time ofpseudo consecutive record(sec))

=(N _(—) pack*2048*8)*(27 M/(SCR _(—) first _(—) next−SCR _(—) first_(—) current))

[0421] In the above formula, “SCR_first_current” is a time (in 1/(27mega) seconds) at which the track buffer of the reproduction apparatusshould output the first pack of the video object, and SCR_first_next isa time (in 1/(27 mega) seconds) at which the track buffer of thereproduction apparatus should output the first pack of the followingvideo object.

[0422] As shown in the above Formulas 10 and 11, the minimum size of thepseudo consecutive record can theoretically be calculated in accordancewith the bit rate of AV data.

[0423] Formula 10 cannot be applied to a case where any defectivesectors exist on the optical disc. Such a case is explained below interms of the value of “N_ecc” required to ensure the uninterruptedreproduction, the “N_ecc” representing the number of ECC blocks in thepseudo consecutive record.

[0424] It is presumed here that the pseudo consecutive record includesECC blocks with defective sectors the number of which is represented as“dN_ecc.” No Av data is recorded into the dN_ecc defective ECC blocksdue to the ECC block skipping which has been described earlier. The losstime Ts generated by skipping the dN_ecc defective ECC blocks isrepresented as “T4*dN ecc,” where “T4” represents the ECC block skiptime for the model shown in FIG. 39.

[0425] With the above description taken into account, to ensure theuninterrupted reproduction of the AV data even if defective sectors areincluded, the pseudo consecutive record need to include as many ECCblocks as represented by the following formula.

[0426] <Formula 12>

N _(—) ecc≧dN _(—) ecc+Vo*(Tj+Ts)/((16*8*2048)*(1−Vo/Vr))

[0427] As apparent from the above description, the size of the pseudoconsecutive record is calculated from Formula 10 when no defectivesector is included, and from Formula 12 when any defective sectors areincluded.

[0428] It should be noted here that when an AV data sequence is composedof a plurality of pseudo consecutive records, the first and last pseudoconsecutive records need not satisfy the Formula 10 or 12. This isbecause the last pseudo consecutive record has no subsequent AV data,and that the uninterrupted reproduction between the first and secondpseudo consecutive records is ensured by delaying the timing of thedecode start, namely by starting supplying data to the decoder after thetrack buffer stores a certain amount of data.

[0429] (3-2) Recording of AV files

[0430] Recording of AV files in the DVD recorder 10 is described indetail.

[0431]FIG. 40 is a flowchart showing the recording process in the DVDrecorder of the present embodiment. The flowchart is the same as FIG. 38except that the step 380 is replaced with step 400 and the step 390 isdeleted.

[0432] The flowchart of FIG. 40 is described concentrating on thedifferences.

[0433] When the user presses the RECORD button or when the “currenttime” reaches the start time of “programmed recording,” a notificationof recording start is sent to the recording/editing/reproducing/controlunit 105 via the user IF unit 106.

[0434] On receiving the notification, the control unit 105 assigns anarea having a size greater than the above-described minimum size as apseudo consecutive record (step 400). More specifically, the controlunit 105 calculates the actual bit rate of the video object using theFormulas 10 and 11. However, here, a predetermined size satisfying theminimum size may be used instead for the sake of conveniences. Thecontrol unit 105 refers to the space bit map and each allocationdescriptor of the file management area to detect unassigned areas on theoptical disc, creates a free space list showing the detected areas, andassigns an area among the detected areas which is larger than theminimum size as a pseudo consecutive record. In doing so, an areaincluding a zone boundary is treated as two unassigned areas, before andafter the zone boundary.

[0435]FIG. 41 shows a free space list. In the drawing, the “startsector” column shows the start sector numbers of the unassigned areas;the “end sector” column shows the end sector numbers of the unassignedareas; and the “attribute” column shows whether the corresponding areasare assigned. The “Free” shown in the drawing indicates that thecorresponding area is not assigned.

[0436] Presuming the minimum size is determined to be about 7 MB (3500sectors), it is found that unassigned area c1 is smaller than thisvalue, and unassigned areas c2 and c3 are both greater than this value.In this case, the recording/editing/reproducing/control unit 105 assignsthe unassigned areas c2 and c3 as pseudo consecutive records.

[0437] The same steps as FIG. 38 follow the above step. It should benoted here that when recording AV data, the AV data recording unit 210uses the unassigned areas located on the innermost side first byreferring to the free space list, followed by the unassigned areas inorder from the innermost to the outermost areas of the optical disc.Also note that the free space list is not recorded on the optical disc.

[0438]FIG. 42 is a flowchart detailing the procedure of assigning thepseudo consecutive record performed in the step 400 of FIG. 40.

[0439] The control unit 105 refers to the space bit map and eachallocation descriptor of the file management area to detect unassignedareas on the optical disc (step 421). In doing so, the control unit 105may disregard areas that are so small to record AV data (e.g.,several-hundred kilobytes in size).

[0440] The control unit 105 creates the free space list based on thedetected unassigned areas (step 422). In doing so, an area including azone boundary is treated as two unassigned areas, before and after thezone boundary. It should be noted here that the control unit 105 judgeswhether an area includes a zone boundary by inquiring the AV file systemunit 103, that is, by issuing the SEARCH_DISCON command shown in FIG.21. The positions of zone boundaries on the optical disc are fixedly setin advance, and are stored and managed by the AV file system unit 103.

[0441] Furthermore, the control unit 105 determines the minimum size ofthe pseudo consecutive record using the Formulas 10 and 11 (step 423).Here, when defective sectors are found, the control unit 105 uses theFormulas 12 and 11. To simplify this process, the control unit 105 maydetermine the minimum size of the pseudo consecutive record using a bitrate of AV data determined in advance in compliance with the picturequality (e.g., a quality classified into “high, “standard,” and “and“time-ensuring” shown in FIG. 24), an expected rate of defectivesectors, and a margin.

[0442] The recording/editing/reproducing/control unit 105 then assignsan area among the detected areas which is larger than the minimum sizeas a pseudo consecutive record, and determines the recording order (step424). The order is determined to be, for example, from the innermostside to the outermost side of the disc so that the seek move is as smallas possible.

[0443] As described above, when recording AV data, the DVD recorder ofthe present embodiment dynamically assigns unassigned areas as pseudoconsecutive records by referring to the space bit map and eachallocation descriptor of the file management area. As a result,different from Embodiment 2, the DVD recorder of the present embodimentdynamically assigns pseudo consecutive records for recording AV data,without recording the pseudo consecutive record assignment managementinformation.

[0444] It should be noted here that in Embodiment 3, the free space listis created for each recording. However, the DVD recorder may create thefree space list when the optical disc is loaded into the optical discdrive, and may update the free space list each time the DVD recorderrecords AV data.

[0445] Also, the DVD recorder may create and record the free space listonto the optical disc, refer to the recorded free space list beforerecording AV data, and update the list after the recording of the AVdata.

[0446] The present invention has been fully described by way of exampleswith reference to the accompanying drawings, it is to be noted thatvarious changes and modifications will be apparent to those skilled inthe art. Therefore, unless such changes and modifications depart fromthe scope of the present invention, they should be construed as beingincluded therein.

What is claimed is:
 1. An optical disc recording apparatus for recordingvideo objects on an optical disc, wherein a recording area of theoptical disc is divided into a plurality of blocks, each of which iscomposed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidoptical disc recording apparatus comprising: a reading unit operable toread the sector information from the optical disc; a detecting unitoperable to detect a series of consecutive unassigned sectors on theoptical disc by referring to the read sector information, a total sizeof the series being no smaller than a predetermined size thatcorresponds to a data amount that ensures the reproduction apparatus foruninterrupted reproduction of the video object; and a recording unitoperable to divide and record a video object onto two or more series ofconsecutive unassigned sectors detected by the detecting unit, and thepredetermined size is the number of blocks which is represented as “N”in the following formula: N=Vo*Tj/((N _(—) sec*8*S _(—)size)*(1−Vo/Vr)), where “Tj” represents a maximum jump time of anoptical pickup of a reproduction apparatus, “Vr” represents an inputtransfer rate of a track buffer of the reproduction apparatus, and “Vo”represents an effective output transfer rate of the track buffer.
 2. Theoptical disc recording apparatus of claim 1 further comprising unitoperable to generate management information showing areas of the opticaldisc where the video object has been recorded by the recording unit. 3.An optical disc recording method for recording video objects on anoptical disc, wherein a recording area of the optical disc is dividedinto a plurality of blocks, each of which is composed of a set of N_secconsecutive sectors, each sector having a size of S_size bytes, theoptical disc records sector information showing data assignment for eachsector on the optical disc, said optical disc recording methodcomprising: a reading step for reading the sector information from theoptical disc; a detecting step for detecting a series of consecutiveunassigned sectors on the optical disc by referring to the read sectorinformation, a total size of the series being no smaller than apredetermined size that corresponds to a data amount that ensures thereproduction apparatus for uninterrupted reproduction of the videoobject; and a recording step for dividing and recording a video objectonto two or more series of consecutive unassigned sectors detected bythe detecting unit, and the predetermined size is the number of blockswhich is represented as “N” in the following formula: N=Vo*Tj/((N _(—)sec*8*S _(—) size)*(1−Vo/Vr)), where “Tj” represents a maximum jump timeof an optical pickup of a reproduction apparatus, “Vr” represents aninput transfer rate of a track buffer of the reproduction apparatus, and“Vo” represents an effective output transfer rate of the track buffer.4. The optical disc recording method of claim 3 further comprising astep for generating management information showing areas of the opticaldisc where the video object has been recorded by the recording unit. 5.A computer-readable recording medium recording a program for recordingvideo objects on an optical disc, wherein a recording area of theoptical disc is divided into a plurality of blocks, each of which iscomposed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidprogram causing a computer to execute: a reading step for reading thesector information from the optical disc; a detecting step for detectinga series of consecutive unassigned sectors on the optical disc byreferring to the read sector information, a total size of the seriesbeing no smaller than a predetermined size that corresponds to a dataamount that ensures the reproduction apparatus for uninterruptedreproduction of the video object; and a recording step for dividing andrecording a video object onto two or more series of consecutiveunassigned sectors detected by the detecting unit, and the predeterminedsize is the number of blocks which is represented as “N” in thefollowing formula: N=Vo*Tj/((N _(—) sec*8*S _(—) size))*(1−Vo/Vr)),where “Tj” represents a maximum jump time of an optical pickup of areproduction apparatus, “Vr” represents an input transfer rate of atrack buffer of the reproduction apparatus, and “Vo” represents aneffective output transfer rate of the track buffer.
 6. Thecomputer-readable recording medium of claim 5 , wherein the programfurther causes the computer to execute a step for generating managementinformation showing areas of the optical disc where the video object hasbeen recorded by the recording unit.
 7. An optical disc recordingapparatus in which an optical disc is inserted, wherein a recording areaof the optical disc is divided into a plurality of blocks, each of whichis composed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidoptical disc recording apparatus comprising: a reading unit operable toread the sector information from the optical disc; a detecting unitoperable to detect a series of consecutive unassigned sectors on theoptical disc by referring to the read sector information, a total sizeof the series being no smaller than a predetermined size thatcorresponds to a data amount that ensures the reproduction apparatus foruninterrupted reproduction of the video object; and a recording unitoperable to divide and record a video object onto two or more series ofconsecutive unassigned sectors detected by the detecting unit, and thepredetermined size is the number of blocks which is represented as “N”in the following formula: N=Vo*Tj/((N _(—) sec*8*S _(—)size)*(1−Vo/Vr)), where “Tj” represents a maximum jump time of anoptical pickup of a reproduction apparatus, “Vr” represents an inputtransfer rate of a track buffer of the reproduction apparatus, and “Vo”represents an effective output transfer rate of the track buffer.
 8. Theoptical disc recording apparatus of claim 7 further comprising unitoperable to generate management information showing areas of the opticaldisc where the video object has been recorded by the recording unit.